Integrated system for powered surgical tools

ABSTRACT

An integrated surgical tool system (30) for energizing different powered surgical handpieces (32, 33). Internal to each handpiece is a non-volatile memory (72) which stores data regarding the operating parameters of the handpiece. This data, includes information about the speeds at which any motor internal to the handpiece should be driven, the maximum current that should be drawn by the handpiece and the maximum internal temperature of the handpiece. The handpiece is plugged into a complementary control console (36). The control console reads the data in the internal memory. Based on the retrieved data and manual control signals, the control console supplies energization signals to the handpiece so as to cause the appropriate actuation of the handpiece.

FIELD OF THE INVENTION

This invention relates generally to powered surgical tools and, moreparticularly, to an integrated system for facilitating the use of anumber of different surgical tools and the use of these tools withdifferent accessories.

BACKGROUND OF THE INVENTION

In modern surgery, powered surgical tools are some of the mostimportant: instruments medical personnel have available to then forperforming certain surgical procedures. Many surgical tools take theform of some type of motorized handpiece to which a cutting accessorylike a drill bit, a burr or a saw blade are attached. These tools areused to selectively remove small sections of hard or soft tissue or toseparate sections of tissue. The ability to use powered surgical toolson a patient has lessened the physical strain of physicians and otherpersonnel when performing surgical procedures on a patient. Moreover,most surgical procedures can be performed more quickly and moreaccurately with powered surgical tools than with the manual equivalentsthat proceeded them.

A typical powered surgical tool system, in addition to the handpiece,includes a control console and a cable that connects the handpiece tothe console. The control console contains the electronic circuitry thatconverts the available line voltage into energization voltage suitablefor powering the motor integral with the handpiece. Typically, thecontrol console is connected to receive a signal from the hand or footswitch used to control the tool; based on that signal, the console sendsappropriate energization signals to the handpiece so as to cause it tooperate at the desired speed.

As the use of powered surgical tools has expanded, so has thedevelopment of different kinds of powered surgical tools that performdifferent surgical tasks. For example, a femoral reamer, used in hipreplacement surgery is a relatively slow speed drill that operates atapproximately 100 RPM, yet it draws a relatively high amount of power,approximately 400 Watts. Neurosurgery requires the use of a craniotomewhich is a very high powered drill that operates at approximately 75,000RPM and that requires a medium amount of power, approximately 150 Watts.In ear, nose and throat surgery, micro drills are often employed. Atypical micro drill rotates between approximately 10,000 and 40,000 RPMand requires only a relatively small amount of power, approximately 40Watts.

As the number of different types of powered surgical tools haveexpanded, it has become necessary to provide each type of handpiece amechanism for ensuring that it receives the appropriate energizationsignals. The conventional solution to this problem has been to provideeach handpiece with its own power console. As can readily be understood,this solution is expensive in that it requires hospitals and othersurgical facilities to keep a number of different consoles available, inthe event a specific set of tools are required to perform a givensurgical procedure. Moreover, in the event a number of differentsurgical tools are required in order to perform a given surgicalprocedure, it is necessary to provide the operating suite with theindividual consoles required by the different handpieces. Having toprovide these different consoles contributes to clutter in the operatingsuite.

An attempt to resolve this issue has been to design consoles that can beused to supply power to different handpieces. While these consoles haveperformed satisfactorily they are not without their own disadvantages.Many of these consoles are arranged so that the medical personnel haveto manually preset their internal electronics in order to ensure thatthey be provided the desired energization signals to the tools to whichthey are connected. Moreover, given the inevitable human error factor,time also needs to be spent to ensure that once configured for a newtool, a console is, in fact, properly configured. Requiring medicalpersonnel to perform these tasks takes away from the time the personnelcould be attending to the needs of the patient.

There have been some attempts to provide surgical tools capable ofproviding some configuration information to the complementary controlconsoles. These tools typically take the form of handpieces with one ortwo resistors that collectively provide one or more analog signals backto the console. The console, based on the magnitude of these analog tooltype signals, is capable of performing some basic tool configurationfunctions such as, identify the type of the tool or cutting instrumentattached thereto. While these powered tool systems have proved useful,they are of limited value in that any significant information about thetool, such as an indication of the maximum power that can be appliedthereto, or the maximum speed at which its motor can be driven must becontained within the complementary console. In order for a console toproperly configure itself for use with a particular handpiece, theconsole must be preloaded with this data. If the console does notcontain this data, the recognition data contained within the tool is ofrelatively marginal value.

Moreover, as the number of powered surgical tools has expanded, so hasthe number of accessory features that can be used with the tools. Sometools, for example are provided with hand switches integral with thetool that allow the physician to control the on/off state of the toolsas well as the speed of the motor internal to the tool. Still other toolsystems are provided with foot switches. This later type of controlarrangement is provided for the convenience of medical personnel who,instead of controlling tool speed with their hands, prefer controllingtool speed with their feet. One reason some foot switch tool controlassemblies are preferred is that it eliminates the need have a handswitch, which is a physical object that some physicians find interfereswith their grasp of the handpiece.

Still other powered surgical tool systems are provided with integratedlight and/or water sources. The light source typically includes sometype of light emitting member attached to the head of the surgical tool.The light source is provided in the event the surgeon requires a highintensity light to be directed onto the surgical site where a surgicaltask is being performed. The water source is typically connected to anirrigation pump. A water source is typically attached to a surgical toolin situations where it. is desirable that the surgical site be irrigatedessentially simultaneously with the execution of the surgical task.

The conventional solution to providing surgical tools with the desiredaccessories has been to design individual tools their own fixedaccessories. Some tools, for example, are provided with hand switcheswhile other tools do not include these switches. Similarly, some toolsare provided with integral conduits for supplying light and/or water tothe surgical site while other tools do not include these attachments. Ina surgical facility, the choice of surgical tool can be a function ofvariables such as physician preference and the type of surgical taskbeing performed. It can be quite costly to provide a number of differenttools, each with its own set of accessory features, in order to makeappropriate accommodation for individual personal preferences andsurgical requirements.

Moreover, the tool accessories typically require their own set ofcontrol signals to regulate their operation. Often this has beenaccomplished by providing the accessories, such as the light and waterunits, with their own control consoles that are separate from thecontrol consoles used to control the application of power to theassociated handpieces. The need to provide these additional controlconsoles further contributes to both the cost of properly equipping anoperating suite and the clutter within the suite.

There have been attempts at reducing tool proliferation by providingsurgical tools with removable hand switches and removable light andwater clips. The hand switches, once removed, reduce some of thestructural components that are bothersome to some surgeons. However,these tools are typically provided with some type of permanent holder tosecure the hand switch in place. These holders still have the potentialof interfering with the grasp of the tools to which they are attached.Moreover, these removable units must still be provided with some type ofcontrol unit. In order to maximize the utility of these removable units,as discussed above, they are often provided with their own controlconsoles. Still another disadvantage of this type of tool assemblies isthat their light and water units have complementary control buttons thatare depressed in order to control the actuation of these units and theirrates of operation. The inclusion of these control buttons further addsto the overall number of control buttons that are presented to thepersonnel in the surgical suite. The presentation of these buttons, whenthey are not needed thus presents surgical personnel with extraneousinformation that may detract their attention from the matters andinstrument controls on which they should be concentrating.

Moreover, recently surgical tools have been developed that havedifferent power requirements than conventional handpieces. For example,for some surgical procedures a physician may wish to use a tool thatincludes a battery pack for applying power. Sometimes, in order to avoidthe inevitable problem of the battery drainage, the surgeon may wish tosubstitute a line-powered power unit for the battery pack. Still othernew tools do not even include traditional electrically powered motors.An example of these tools are surgical lasers and ultrasonic scalpels.These tools have their own power requirements and complementaryaccessories. In order to make these tools available to surgical.personnel, it has been necessary to bring an additional set of controlconsoles into the surgical suite. Having to provide this additionalequipment has further contributed to the cost and complexity ofequipping a surgical suite.

SUMMARY OF THE INVENTION

This invention relates to an improved integrated system for poweredsurgical tools that facilitates the use of tools having different powerand control signal requirements and that allows the individual tools tobe used with different combinations of accessory units.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is pointed out with particularity in the claims. The aboveand further features of the invention may be better understood byreference to the following description taken in conjunction with theaccompanying drawings in which:

FIG. 1 depicts the basic components of the integrated surgical toolsystem of this invention;

FIG. 2 is a cross sectional view of one handpiece that can be employedas part of the integrated surgical tool system;

FIG. 3 is an exploded view of the internal components of the handpiecemotor;

FIG. 4 is a bottom view illustrating how the flex circuit is housed in aback shell of a handpiece;

FIG. 5A is a cross sectional view of a basic cable used to provideenergization signals to a handpiece and that serves as a conduit forcontrol signals exchanged between the handpiece and the control console;

FIG. 5B is a detailed cross sectional view of a single motor conductorwithin the cable of FIG. 5;

FIG. 6 is an exploded view illustrating how a removable hand switch isattached to a handpiece;

FIG. 7 is an exploded view of the components forming the removable handswitch;

FIG. 8 is an exploded view illustrating how a removable light-and-waterclip is attached to a handpiece;

FIG. 9 is an exploded view illustrating the components forming thelight-and-water clip of FIG. 8;

FIG. 10 is a cross sectional view of the control cable used with thelight-and-water clip of FIG. 9;

FIG. 11 is a cross sectional view of the console-end plug of the controlcable used of FIG. 10;

FIG. 12 is a cross sectional view illustrating how the cable of FIG. 10is coupled to both a handpiece and a light-and-water clip;

FIG. 12A is a cross sectional view illustrating the electrical couplingbetween the cable and the light-and-water clip;

FIG. 12B is a cross sectional view illustrating the water couplingbetween the cable and light-and-water clip;

FIG. 13 is a block diagram of the data stored in the non-volatile memorywithin a handpiece;

FIG. 14 is a diagram of illustration how the maximum torque of the motorin the handpiece can vary as a function of the speed of the handpiece;

FIG. 15 is a diagram representative of the data fields within theread/write memory within a handpiece;

FIG. 16 is a blue print indicating how FIGS. 16A and 16B are assembledto form a basic block diagram of the elements forming the controlcircuit within the console of the integrated tool system;

FIG. 17 is a blue print indicating how FIGS. 17A and 17B are assembledto form a block diagram of the main components of the main processor ofthe control circuit;

FIGS. 18A, 18B and 18C are schematic diagrams of the components formingthe handpiece interface of the control circuit;

FIG. 19 is a block diagram illustrating how FIGS. 19A and 19B areassembled to form a block diagram display-input/output controller of thecontrol circuit;

FIG. 20 is a block diagram illustrating how FIGS. 20A and 20B areassembled to form a block diagram of the motor controller and currentsensing circuit of the control circuit;

FIG. 21 is a schematic diagram of the motor driver of the controlcircuit;

FIG. 22 is a block diagram of the memory accessed by the microprocessorwithin the main controller illustrating the modules that are selectivelyexecuted by the microprocessor during the operation of the system;

FIG. 23 is a flow chart of the primary processing steps executed by themicroprocessor within the main controller based on the instructionscontained within the main module;

FIG. 24 is an illustration of the sign-on screen, image, presented bythe control console when the system is initialized;

FIG. 25 is graphical illustration of how the excess current limit timeout period for a handpiece motor varies as a function of the currentoperating speed of the handpiece; FIG. 26 is an illustration of theprimary user time image presented by the control console after thesystem is initialized and when at least one handpiece is plugged intothe control console when the system is initialized;

FIG. 27 is an illustration of the cable only/no handpiece connectedimage presented by the control console when there is a cable without acomplementary handpiece attached to the control console and anindividual indicates an interest in actuating the cable;

FIG. 28 is a flow chart of the processing steps executed by themicroprocessor within the main controller based on the instructionscontained within the speed set module;

FIG. 29 is a flow chart of the processing steps executed by themicroprocessor within the main controller based on the instructionscontained within the current set module;

FIG. 30 is an illustration of the run time image presented by thecontrol console when a handpiece is actuated; and

FIG. 31 is an illustration of the surgeon selector image presented bythe control console; and

FIG. 32 is a block diagram of a set of accessory head data fields thatmay be present in the handpiece memory.

DETAILED DESCRIPTION

FIG. 1 depicts the basic components of the integrated surgical toolsystem 30 of this invention. system 30 includes two surgical tools,referred to as handpieces 32 and 33. Each handpiece 32 and 33 containsan electrically driven motor. A cutting attachment, here a burr 34, iscoupled to handpiece 32 so as to rotate with the actuation of the motor.A saw 35 serves as the cutting attachment for handpiece 33. The powerfor energizing the motor within the handpiece 32 or 33 comes from acontrol console 36. The control console 36 selectively energizes thehandpieces 32 and 33 in response to user-entered commands and furthermonitors the operation of the handpieces. A touch screen display 37integral with control console 36 serves as the interface through whichinformation about the handpieces 32 and 33 is presented to surgicalpersonnel and through which some commands used to control the handpiecesare supplied to the control console.

The on/off operation and speed of handpiece 32 is controlled by aremovable hand switch 39 fitted around the outside of the handipiece. Acable 43 connected between handpiece 32 and control console 36 providethe conductive paths for the signals exchanged between the handpiece andthe console. These signals include both the signals generated by thehandpiece 32 in response to the state of the hand switch 39 and theenergization signals that are applied to the motor internal to thehandpiece. Handpiece 33 is not fitted with a hand switch. Instead, theon/off state and motor speed of handpiece 33 are controlled by thedepression of pedals 44 integral with a foot switch assembly 46 alsopart of system 30.

The surgical site to which handpiece 33 is applied is illuminated andselectively irrigated by a light-and-water clip 45 that is removablyattached to the handpiece 33. The water that is discharged fromlight-and-water clip 45 is forced through the clip by a pump 40 that isconnected to a source 41 of suitable sterile water. In FIG. 1, pump 40is depicted as being unit that is removably mountable within controlconsole 36. The water is supplied from pump 40 to the light-and-waterclip 45 through a cable 47 that extends from control console 36 and thatfurther includes the conductors over which the signals needed to controlthe handpiece 33 and the light integral with clip 45 travel. Theactuation of the light and the discharge of water through the clip 45are both regulated by control console 36 based on commands enteredthrough the foot switch assembly 46.

When the system 30 determines that a handpiece 32 or 33 has been pluggedinto the system, control console 36 reads data stored in memory unitsinternal to the handpiece. Based on the retrieved data, the controlconsole 36 configures itself so that it can supply the appropriatelyenergization signals to handpiece 32 or 33. As part of theinitialization process, the control console presents a set ofinstructions on the display 37 that direct the medical personnel toprovide information about any accessories that may be used inconjunction with the handpieces 32 and 33. Once the requisiteinstructions are received, the control console then regulates theoperation of the handpieces 32 and 33 based on the state of the handswitch 39, the pedals 44 and commands entered through the display 37.

FIGS. 2 and 3 depict the basic structure of a handpiece, here handpiece32, that is part of the system 30 of this invention. Handpiece 32includes a cylindrical motor housing 50 in which a motor 52 is housed.Motor housing 50 is formed to have an open rear end 54 through which thecomponents forming motor 52 are inserted in the housing. Motor housing50 is further formed to define a neck 56 at the front end of the housingthat has a reduced diameter relative to the main body of the housing. Inthe depicted version of the invention motor 52 is a brush less, Hapless(sensor less) DC motor. Motor 52 includes three separate windings whichare represented by a sleeve-like field coil assembly 58. Integral withfield coil assembly 58 is a lamination stack 59 which is located aroundsubstantially around the entire outside of the field coil assembly. Arotor 600 is rotatably fitted inside the field coil assembly 54. A setof permanent magnets 62 are secured to the outside of the rotor 56 so asto be located in close proximity to the field coil assembly.

The motor rotor 60 extends out of the neck 56 of the motor housing 50. Abearing assembly 64 fitted in the neck 56 around the rotor 60 holds therotor steady. A drill housing 66 is fitted around the neck 56 of themotor housing 50 so as to extend around the exposed end of the rotor 56.A coupling assembly 68 is located in the drill housing 60. The couplingassembly, which is not part of this invention, releasable secures theburr 34 or other cutting accessory to the rotor 56 so that the accessorywill rotate in unison with the rotor.

Two memory units 72 and 74 are fitted in the motor housing 50 ofhandpiece 32. A first memory unit, memory unit 72, is a read onlymemory. In one preferred version of the invention memory unit 72 is anon-volatile random access memory (NOVRAM), a one-time write memory,that has a 2k byte storage capacity. NOVRAM 72 is written to during themanufacture of the handpiece 32 and the data stored therein is retrievedby control console 36 when handpiece 32 is attached to the console. Thesecond memory unit, memory unit 74, is a non-volatile, erasable randomaccess memory. In one preferred version of the invention, memory unit 74is an electronically erasable programmable read memory (EEPROM) that hasa storage capacity of 256 bits. EEPROM 74 is written to by the controlconsole 36 as a result of the use of the handpiece 32. The datacontained in EEPROM is both read by control console 36 as part of itsinitial internal configuration process and is further read whenmaintenance work is performed on the handpiece 32. In one version of theinvention, a DS2505P manufactured by Dallas Semiconductor is employed asthe NOVRAM 72 and a DS2430AP from the sane source is used as the EEPROM74.

The NOVRAM 72 and EEPROM 74 are both attached to a flex circuit 76 thatis located in the motor housing 50. The flex circuit 76 is formed from anon-conductive material that will not breakdown when subject to thesterilization environment to which the handpiece 32 is exposed(Saturated steam at 270° F. at 30 psi). One suitable material from whichthe flex circuit 76 is formed is polyamide like material which is soldby the DuPont Company under the trademark Powerflex AP. Copper traces 78formed on the flex circuit 76 form the conductive paths both to thememories 72 and 74 and to the other components mounted on or connectedto the flex circuit.

The flex circuit 76 is primarily fitted between the lamination stack 59and a sleeve-like plastic back shell 82 that is fitted around the fieldcoil assembly 58. In the illustrated version of the invention, flexcircuit 76 is shaped to have a circular head section 84. As discussedhereinafter, the external electrical connections to the flex circuit 76are made through the head section 84. An elongated, generallyrectangularly shaped spine 86 extends away from the head section 84 ofthe flex circuit 76. Two aligned arms 88 extend perpendicularly awayfrom the spine 86 a short distance away from the head section 84. NOVRAM72 is attached to a first one of the arms 88 and EEPROM 74 is attachedto the second of the arms 88.

Flex circuit 76 has a rectangularly shaped main body 90 that is centeredaround the end of the spine 86 and that is spaced away from the arms 88.The main body 90 of flex circuit 76 is the portion of the flex circuitthat is located between lamination stack 59 and back shell 82. Carriedon the main body 90 of the flex circuit 76 are the conductive traces 78that provide the electrical connections to the three windings formingfield coil assembly 58. In order to facilitate the electricalconnections to the windings the end of the main body 90 distal from thehead section is formed with three arrow head shaped cutouts 97 to whichtraces 78 extend.

Also attached to the main body 90 of the flex circuit 76 are twoadditional devices which are specific to the handpiece in which the flexcircuit is fitted. In handpiece 32, a first one of the devices is a Halleffect sensor 94. The Hall effect sensor 94 monitors the position of amagnet internal to the hand switch 39 when the hand switch used tocontrol the on/off state and speed of the motor 50. The second device isa temperature sensor 96 that monitors the internal temperature of thehandpiece 32. In the illustrated version of the invention, Hall effectsensor 94 is mounted in a cutout space 98 formed along the perimeter ofthe flex circuit main body 90 that is distal from the head section 84 ofthe flex circuit 76. Temperature sensor 96 is secured to the surface ofthe flex circuit 76 that is directed inwardly towards the field coilassembly 58. Temperature sensor 96 is further attached to the flexcircuit so as to be located immediately inside the edge of the main body90 that is furthest from the head section 84. Consequently, when theflex circuit is fitted in handpiece 32, temperature sensor 96 is locatedadjacent the forward end of the field coil assembly 58 so as to also bein relatively close proximity with the neck 56 of the motor housing 50and the bearing assembly 64 fitted therein.

In some versions of the invention, a single conductive trace 78 servesas the address/data bus for both NOVRAM 72 and EEPROM 74. In theseversions of the invention a resistor 102 may be series connected intothe branch of the trace that extends to one of the memories. Also, it istypically necessary to provide a reference voltage to the sensors 94 and96 secured to the flex circuit 76. As will be described hereinafter,this reference signal is supplied by the control console 36. Typically,in order to minimize spiking of the reference voltage, a capacitor 104is connected across the conductive trace 78 over which the referencevoltage is carried on the flex circuit and a complementary trace 78 thatserves as en analog signal ground.

In order to ensure that the data within memories 72 and 74 is accuratelyread by control console 36, flex circuit 76 is provided with anadditional conductive trace 78 that functions as a dedicated digitalground conductor. This digital ground conductor is only connected to theground pins of memories 72 and 74. This conductor is separate from theanalog ground conductor to sensors 94 and 96. It is also necessary thatthe digital ground conductor and the associated signal conductor that isconnected to memories 72 and 74 be configured as a twisted pair of wiresto the maximum extent possible, both on the flex circuit 76 and in thecable 43 connected to the control console 36.

The back shell 82, now described with reference to FIGS. 3 and 4, has amain body 106 with an open front end 108 to facilitate the fitting ofthe motor 52 and assembled flex circuit 76 in the shell. The main body106 of the back shell is further formed to have outwardly projecting,longitudinally extending ribs 110. The ribs 110 provide a compressionfit between the back shell 82 and the adjacent inside wall of the motorhousing 50. In some versions of the invention ribs 110 are at leastpartially sheared off when the back shell 82 is fitted in the motorhousing 50. Integral with the main body 106 of the back shell 82 is anend cap 112. End cap 112 is formed with a bore 113 coaxially alignedwith the main body 106 through which the rear portion of the rotor 60 ofthe motor 50 extends.

Back shell 82 is further formed with an elongated, slot-like opening 114that extends the length of the shell through both the main body 106 andend cap 112. opening 114 is dimensioned to allow the flex circuit 76 tobe positioned so that the head section 84 can be spaced away from theend of the end cap 112, the spine 86 is seated in the opening 114 andthe main body 90 disposed against the inside surface of the main body106 back shell. When the flex circuit 76 is so fitted in the back shell82, the arms 88 of the flex circuit are located around the outside ofthe end cap 112. The ends of the arms 88 are then seated in slots 116formed in the end cap 112, best seen by reference to FIG. 4. In thedepicted version of the invention, end cap 112 is further formed withflat surfaces 118 that extend from opening 114 to the slots 116. Flatsurfaces 118 are recessed relative to the outsider diameter of the restof the end cap 112. Memories 72 and 74, resistor 102 and capacitor 104are attached to flex circuit 76 so as to be directed towards flatsurfaces 118 of the back shell 82. Thus, owing to the positioning of thememories 72 and 74, resistor 102 and capacitor 104 in the relativelyopen spaces defined by surfaces 118, once the handpiece 32 is subjectedto the sterilization process, the vapor introduced around thesecomponents is able to be drawn away therefrom relatively quickly.

Returning to FIGS. 2 and 3, it can be seen that a front shell 122 coversthe outer surface of the flex circuit 76 that projects forward of theback shell 82 and is seated in opening 114 formed in the back shell.Front shell 122 has a ring shaped head section 126 that is seated aroundthe exposed portion of the main body 90 of the flex circuit 76. A stem127 formed integrally with the head section 126 extends rearwardlytherefrom. The front shell 122 is positioned relative to the headsection so that the front shell stem 127 is seated in the opening 114 inthe back shell so as to cover the portion of the flex circuit seated inthe opening.

A rear bearing housing 128 is fitted over the end of the end cap 112 ofthe back shell 82. Rear bearing housing 128 has a relatively largediameter base 130 with an outer diameter that allows it to be fitted inrelatively close proximity against the inside wall of the motor housing50. The base 130 of rear bearing housing 128 is formed to define anelongated slot 131 in which the spine 86 of the flex circuit 76 isseated. The inside of the base 130 defines a void space 134 in which thehead section 84 of the flex circuit 76 is seated. A reduced diameter,bearing sleeve 135 extends forward from the base 130 into the bore 113defined in the back shell end cap 112. A rear bearing assembly 132 islocated in bearing sleeve 135. Rear bearing assembly 132 extends betweenthe bearing sleeve 135 and the end of the motor rotor 60 for holding therotor for stable rotation.

A one-piece, cylindrical socket holder 137 is fitted in the end of themotor housing 50 so as to cover the rear bearing housing 128 and theexposed head section 84 of the flex circuit 76. Socket holder 137 has atube-shaped outer body 138 that is dimensioned to be compression fittedagainst the inside wall of the motor housing 50. The outer body 138 isformed with an outwardly projecting, circumferential flange 140 locatedat the rear end thereof that limits forward movement of the socketholder 137. Outer body 138 is further formed to define an elongated slot141 that extends along the inside wall of the outer body to facilitatethe proper coupling of the cable 43 to the socket holder 137.

A head ring 142 extends forward from the outer body 138 of the socketholder 137. Head ring 142 has a diameter less than the diameter of theouter body 138. More particularly, the head ring 142 of the socketholder 137 has an outer diameter that allows the head ring to be fittedagainst the inside circumferential wall of the base 130 of the rearbearing housing 128 that defines space 134. An O-ring 144 located aroundthe outer body 136 of the socket holder 137 seals the inside of themotor housing 50. In the illustrated version of the invention, O-ring144 is seated in an annular slot 146 defined along the forward outeredge of the outer body 136.

Socket holder 137 further includes a solid, cylindrical socket boss 148.Socket boss 148 extends rearward from the head ring 142 of the socketholder 137 and is inwardly spaced from the outer body 138. Socket boss148 is formed with a center bore 150 in which a head cap screw 152 isseated. The tip end of the head cap screw 152 is seated in acomplementary bore, in the center of the rear bearing housing 128. A setof conductive sockets 154 are seated in a ring of counter-tapered bores148 formed in a circular ring around the center bore 150. The socketsprovide the conducive paths from the cable 43 to the flex circuit 76.The tip ends of the sockets 154 are seated in holes 156 formed in thehead section 84 of the flex circuit 76.

FIG. 5A is a cross sectional view of the cable 43 that contains theconductors over which signals are exchanged with a handpiece such ashandpiece 32. Cable 43 has an outer jacket 160 formed of insulatingmaterial such as silicone rubber. Immediately inside jacket 160 is abraided shield 162 formed of tinned copper. Within shield 162 are theconductors over which energization signals are applied to the handpiecemotor 50, the memories 72 and 74 are accessed and the sensors 94 and 96are monitored. In the illustrated version of the invention, wherein thehandpiece motor 50 is a three-winding, brush less, Hapless (sensor less)motor, cable 43 is provided with three motor conductors 164 each ofwhich is tied through flex circuit 76 to a separate one of the windingsforming the field coil assembly 58. Six individually insulated signalconductors 166 are provided for serving as the signal path between thecontrol console 36 and the memories 72 and 74 and the sensors 94 and 96.

As seen by reference to FIG. 5B, each motor conductor 164 includes aconductive core 168 formed of copper. An insulator 170 is locatedimmediately around the core 168. A spiral shield 172 is located aroundthe insulator 170. An insulating jacket 174 that extends around shield172 serves as the outer cover for each conductor 164. Returning to FIG.5A it can be seen that strands of polyester filler 176 providecushioning around conductors 164 and 166. The conductors 164 and 166 aswell as the strands of filler 176 are wrapped in PTFE tape 178. Jacket160 and shield 162 are fitted around the wrapped sub-assembly.

FIG. 11 depicts the male plug 177 used to connect cable 47 to controlconsole 36. Plug 177 has the same basic components as found in the maleplug used to attach cable 43 to the control console 36. Terminal pins179 are connected to conductors 164 and 166 within the cable provide theelectrical connections to complementary socket openings, (notillustrated), on the face of the control console 36. Two of the terminalpins 179 that extend into complementary socket openings in the controlconsole are shorted together. As will be discussed hereinafter, thesignal that the control console 36 asserts through the shorted pins 179is used by the control 36 console to determine whether or not a cable 43or 47 is attached to a control console socket.

An insulated handpiece plug 180 (FIG. 6) provides the connections at theopposite end of the cable 43 between the cable and the handpiece 32.Handpiece plug 180 is provided with a number of pins 181 (FIG. 12) thatprovide the conductive connections between the conductors 164 and 166 inthe cable 43 and the sockets 154 in the handpiece 32. Handpiece plug 180is provided with a single spline 308 (seen in FIG. 9 with respect toplug 242 of cable 47). The spline has a generally rectangularly shapedprofile that extends the length of forward portion of the head that isfitted. into socket holder 137. The spline is designed to be fitted intothe complementary slot 141 formed in the socket holder 137 to ensureproper alignment of the pins of the cable 43 with the sockets 154 in thehandpiece 32.

The removable hand switch 39 attached to handpiece 32 is now describedby reference to FIGS. 6 and 7. Hand switch 39 includes a slip ring 184that is removably fitted over the motor housing 50 of handpiece 32. Alever arm 186 is pivotally secured to slip ring 184 so as to extendforward along the length of the handpiece 32. A torsion spring 188located between slip ring 184 and lever arm 186 biases the lever arm sothat it is normally pivoted away from the handpiece. A magnet 190 isfitted in lever arm 186. The position of the magnet 190 is monitored byHall effect sensor 94 so as to as an indication of the desired operatingspeed of the motor 50 internal to the handpiece 32.

The slip ring 184 has a plastic, sleeve like main body 192 that isdesigned to be releasable compression secured over the motor housing 50.In order to ensure a proper fit of the hand switch, the main body 192 ofthe slip ring 184 is shaped to have an inside diameter that is slightlyless than the outside diameter of the motor housing 50. The main body192 of the slip ring 184 further has an elongated slot 194 that extendsthe length of the body in order to facilitate the removable clampingaction of the slip ring 184 to the handpiece.

Main body 192 of slip ring 184 is also formed with a solid tab 196,(shown in phantom,) that extends inward from the rear end of the mainbody 192 towards the center axis of the main body. Tab 196 isdimensioned to prevent the slip ring from being fitted over the frontend of a handpiece 32 or 31. When cable 43 is coupled to handpiece 32,of the slip ring 184 and radially inward relative to the main body. Theinward-directed end of tab 196 is configured to be seated in acomplementary cut-out 185 formed in the handpiece plug 180 of the cable43. The seating of the slip ring tab 196 in cut-out 185 formed in thehandpiece plug 180 ensures that the hand switch magnet 190 is alignedwith the radial line relative to the center axis of the handpiece alongwhich the complementary Hall effect sensor 94 is located.

Lever arm 186 is formed out of complementary upper and lower shells 198and 200, respectively, that are ultrasonically welded together. Uppershell 198 has a tail end 202 that is located between two parallel,spaced apart mounting tabs 204 that extend outwardly from the main body192 of the slip ring. 184. A pin 206 that extends through alignedopenings in the tabs 204 and in the tail end 202 of the lever arm uppershell 198 secures the lever arm 186 to the slip ring 184. Torsion spring188 is fitted around pin 206. In order to prevent spring 188 fromcompressing against pin 206, a sleeve-like mandrel 208 is fitted in thespring and the pin is rotatably fitted in the mandrel.

Magnet 190 is housed in a movable holder 212 mounted in the lever arm186. Holder 212 has two spaced apart, longitudinally extending parallellegs 214. A cross web 216 extends between the legs 214. The magnet 190is mounted in a support collar 218 that is mounted to the cross web 216.In the illustrated version of the invention, magnet 190 is positioned toextend through an elongated slot 219 formed in the lower shell 200. Thelegs 214 of the holder 212 are mounted in grooves 220 formed in thelower shell 200 of the lever arm 186. Grooves 220 have a greater lengththan the complementary legs 214 so as to allow the longitudinal movementof holder 212.

The position of holder 212 is set by the manual displacement of opposedtabs 222 that are attached to cross web 216 and that project outwardlyfrom lever arm 186. Holder 212 thus allows the magnet 190 to bepositioned in a first position relative to the longitudinal axis of thehandpiece 32 wherein the magnet is spaced from the complementary Halleffect sensor 94 and a second position wherein it is longitudinallyclosed to the sensor. Thus, the magnet is placed in the first position,a safety position, so as to prevent unintended actuation of the motor 52in the event the lever arm 186 is inadvertently depressed. only whenmagnet 190 is in the second position, a run position, will thedepression of the lever arm 186 bring the magnet close enough to Halleffect sensor 94 so that the sensor will detect the proximity of themagnet. In the described version of system 30, the holder magnet 190 isin the safety position when it is positioned toward the rear end of thehandpiece 32.

In the illustrated version of the invention, the far ends of the legs214 of holder 212 are provided with outwardly curved feet 224. The lowershell 200 is formed with notches 226 at the ends of the grooves 220 inwhich the feet seat when the holder is placed in the safety position. Asecond pair of opposed notches 227 are formed integrally with thegrooves forward of the first pair of notches. This seating of the feet224 in the notches 226 or 227 places a resistance on the movement of theholder 212 from, respectively, the safety position or the run position.The imposition of this resistance prevents the unintended movement ofthe magnet 190 from the position in which it is placed.

An extender unit 230 is retractably seated in lever arm 186. Theextender unit 230 is provided to facilitate the use of the hand switch39 by physicians with different hand sizes and/or different techniquesfor holding the handpiece 32. Extender unit 230 includes a U-shapedguide rod 232. The opposed legs of guide rod 232 are slidably fitted incomplementary openings 234 formed in the front of the upper shell 198 ofthe lever arm 186. A head piece 236 is attached to the exposed head ofguide rod 232 so as to define a finger rest: surface for the surgeon toplace his/her finger. The opposed ends of the legs of the guide rod 232are bent inwardly to prevent the extender unit 230 from being totallywithdrawn from the lever arm 186.

The light-and-water clip 45 that is secured to handpiece 33 is nowinitially described by reference to FIGS. 8 and 9. Light-and-water clip45 includes a rear shell 240 that is secured to a complementaryhandpiece plug 242 attached to one end of cable 47. A flexible siliconcarrier tube 244 extends forward from the rear shell 240. Carrier tube244 defines the conduits through which the irrigating water flows and inwhich the conductors that carry the illuminating voltage for the lightbulb are seated. The head end of the carrier tube 244 is attached to afront shell 246 that is snap-fitted to the forward end of the handpiece33. A bulb 248 is seated in the front shell 246 for illuminating thesurgical site. A rigid outlet tube 250 is attached to the front shell246 for providing a fluid conduit through which the irrigating water isdischarged onto the surgical site.

Rear shell 240 of light-and-water clip 45 includes upper and lowerhalves 252 and 254, respectively, that are secured together. Seatedinside a cross web 256 formed in the lower half 254 of shell 240 are twooutwardly directed conductive pins 258. Pins 258 provide the electricalconnection to the handpiece plug 242. A rigid water inlet tube 260extends outwardly from cross web 256 to provide a conduit for theirrigating water. As can be seen by reference to FIG. 9), the lower half254 of rear shell 240 is provided with legs 262 that extend rearward ofcross web 256. Legs 262, in addition to facilitating the coupling ofclip 45 to handpiece plug 242, protect pins 258 and tube 260 so as toprevent the exposed ends thereof from being inadvertently bent.

Carrier tube 244 is clamped at one end between the upper and lowerhalves of rear shell 240. The carrier tube 244 is formed with a firstconduit 264 in which the water inlet tube 260 is fitted. carrier tube244 has a second conduit 266 extending the length thereof that has adumbbell-shaped profile. Insulated conductors 268, shown in phantom, arefitted in the opposed ends of conduit 266. Conductors 268 are connectedto pins 258 and serve as the conductive paths over which theenergization signals are applied to the bulb 248.

It is anticipated that carrier tube 244 will have a length that willallow the associated front shell 246 of light-and-water clip 45 to beattached to handpiece 33 forward of the motor housing. Moreover, theflexible nature of carrier tube 244 allows the front shell 246 to berotated relative to the fixed position of the rear shell 242. Thisallows the bulb 248 and water outlet tube 250 to be selectivelypositioned by the surgeon around the circumference of the handpiece 33.

Front shell 2445 of light-and-water clip 45 has a main frame 270 and acomplementary cover 272 that is snap-fitted over the main frame. Mainframe 270 is shaped to have an approximately C-shaped clamping member274 that is dimensioned to be snap fitted over the handpiece 33. A headpiece 276 is attached to the clamping member 274. The shell cover issnap fitted over head piece 276 so as to facilitate the securing of theforward end of carrier tube 244 therebetween. Head piece 276 is formedwith a first bore 278 in which bulb 248 is seated. (Not shown are theconnections between bulb 248 and the conductors 268 in the carriertube.) A heat shield 280 is fitted around bulb 248 to prevent the heatgenerated by the bulb from radiating.

Outlet tube 250) is seated in a second bore 282 formed in head piece276. In the depicted version of the invention, outlet tube 250 has twoopposed sections that are parallel and axially offset from each otherand an intermediate section that connects the opposed sections. Theportion of tube 250 that extends rearward from head piece 276 is fittedinto the conduit 264 in carrier tube 244 for receiving the irrigatingwater. The opposed end of outlet tube 250 projects forward from frontshell 246 for delivering the water to the surgical site.

In preferred versions of the invention both the rear shell 240 and frontshell 246 of light-and-water clip 45 are shaped so that the thickestsections thereof extend out no further than 0.5 inches from the adjacentoutside surface of the handpiece to which they are attached. In stillmore preferred versions of the invention, these shells extend out nomore than 0.3 inches. The front shell clamping member 274 has a lengthno greater than 0.6 inches. The carrier tube 244 that serves as theconduit for the water and conductors has, in many versions of theinvention a maximum width of 0.4 inches and a top height of 0.25 inches.In more preferred versions of the invention the maximum limits of thesedimensions are 0.25 and 0.2 inches respectively. Collectively, thesefeatures ensure that the coupling of light-and-water clip 45 to ahandpiece does not significantly interfere with handling of thehandpiece.

Cable 47, through which signals are exchanged with handpiece 33 andwater delivered to light-and-water clip 45, is now described byreference to FIG. 10. Cable 47 has the same basic outer jacket 160,braided shield 162 and motor conductors 164 described with respect tocable 43. An irrigation tube, 286 extends longitudinally down the centerof cable 47. Cable 47 is also provided with nine signal conductors 166arranged in groups of bundles of three. The cable 47 is constructed sothat the motor conductors 164 and bundles of signal conductors 166 arelocated are alternatingly and circumferentially arranged around theirrigation tube 286. Strands of polyester filler 176 are locatedadjacent irrigation tube 286 to separate the motor conductors 164 andbundles of signal conductors 166 from each other. Conductors 164, 166,filler strands 176 and irrigation tube 286 are wrapped in PTFE tape 178.

FIG. 11 illustrates a console plug 288 attached to one end of cable 47for connecting the cable to control console 36 and pump 40. The plug 288has generally a metal or plastic body designed to be fitted into acomplementary socket, (not illustrated,) mounted in the face of thecontrol console 36. One end of cable 47 is fitted in the opposed end ofthe plug 288. A solid pin holder 290 is mounted inside plug 288. Theconductive pins 179 that provide the electrical connection between thecontrol console 36 and the conductors 164 and 166 are mounted to pinholder 290 so as to extend outwardly therefrom. It should be recognizedthat plug 288, in addition to having sufficient conductive pins 179 tofacilitate required connections to the motor and devices internal to thehandpiece 33, also has additional pins to provide an energizationvoltage to the bulb 248 mounted in clip 45.

Console plug 288 is further formed with an inlet stud 292 through whichirrigating water from pump 40 is introduced into cable 47. Inlet stud292 extends perpendicularly away from the main axis of the plug, theaxis along which pins 179 are oriented. Inlet stud 292 is formed with abore 293 designed to receive a complementary outlet tube 294 (FIG. 1)from the pump 40. An L-shaped connector tube 296 provides the fluidcommunication path from inlet stud 292 to tube 286 within cable 47. Oneend of connector tube 96 is fitted in an inwardly directed mounting stud298 that is axially aligned with inlet stud 292. More specificallyconnector tube 296 is fitted in a bore 300 formed in stud 298 so thatthe tube is open to the bore 293 in the inlet stud 292. The opposed endof connector tube 296 is fitted into an extension 302 of irrigation tube286 that extends rearward of the end of cable 47.

FIGS. 9, 12, 12A and 12B depict the structure of handpiece plug 242 ofcable 47 and how the plug is connected to handpiece 33 andlight-and-water clip 45. Plug 242 includes a main body 306 formed ofplastic to which the end of cable 47 is attached. Main body 306 isformed with a solid pin holder 307 that is dimensioned to receivedwithin the outer body 138 of the socket holder (FIG. 2) attached to theend of the handpiece. The pins 181 that provide the electricalconnections to the handpiece are mounted in pin holder 307 and extendforwardly therefrom. As seen best in FIG. 12, the main body 306 of theplug 242 is further shaped to have an outwardly directed spline 308.Spline 308 seats in complementary slot 141 to facilitate properalignment of pins 181.

Handpiece plug 242 further includes a head 310 that is attached to theoutside of the main body 306 so as to be located diametrically oppositethe spline 308. Head 310 is provided with two conductive sockets 312.Sockets 312 are positioned to receive the complementary conductive pins258 that extend rearwardly from the rear shell 240 of clip 45. Thesignal conductors 166 in cable 47 that supply the energization currentto the bulb 248 are attached to the sockets 312, (connections notshown).

The head 310 of handpiece plug 242 is further formed with a forwarddirected outlet bore 314 that is located between and slightly abovesockets 312. Outlet bore 314 is dimensioned to receive the water inletline 260 that extends from the light-and-water clip 45. A duck-billedseal 316 is seated in bore 314 and positioned to be opened by inlet line260. Seal 316 thus prevents water from being discharged from cable 47when there is no light-and-water clip 45 attached and opens to allowliquid flow when the clip is in place. Water from cable 47 is directedinto bore 314 through an extension line 318 integral with irrigationtube 286 that extends from the end of cable 47. The extension line 318is coupled into a sealed chamber 320 formed in the head 310 of thehandpiece plug 242 from which bore 314 extends. In the depicted versionof the invention, chamber 320 is dimensioned so that extension line 318is coupled into the chamber at a position that is closer to thelongitudinal axis of the associated handpiece than the position fromwhich bore 314 extends from the chamber.

Legs 262 that extend rearward from the light-and-water clip 45 securethe clip to the head 310 of the handpiece plug 242. Each leg 262 isformed with an inwardly directed foot 322. The feet 322 seat againstopposed inwardly directed steps 324 formed in the handpiece plug head310 forward of the forward face of the head. Feet 322 are pivoted awayfrom the handpiece head 310 by the manual inward compression of thesides of the lower half 254 of the rear shell of light-and-water clip45.

Returning to FIG. 1, the structure of the foot switch assembly 46 is nowdiscussed. In the depicted version of the invention, foot switchassembly 46 has five pedals 44a, 44b, 44c, 44d and 44e. Pedals 44a and44b which are opposed right and left main pedals are relatively large insize are spring biased so as to assume a normally fully extendedposition. Pedals 44a and 44b carry magnets, (not illustrated) thepositions of which are monitored by complementary Hall effect sensors327 (one shown in phantom). The selective depression of pedals 44a and44b actuates the associated handpiece 32 or 33. More particularly, inone configuration of the system, the depression of pedal 44a is used tocause the associated handpiece motor to rotate in a first directionwhile the depression of pedal 44b is used to cause the handpiece motorto rotate in the opposite direction. Alternatively, the system 30 can beconfigured so that depression of one pedal 44a or 44b causes theassociated handpiece motor to rotate in a single direction and thedepression of the other pedal is used to cause the motor to engage inoscillatory rotation. A NOVRAM 329 (shown in phantom) internal to thefoot switch assembly stores data about the characteristics of the outputsignals of the particular sensors 327 mounted in the assembly.

Pedals 44c, 44d, 44e are located above pedals 44a and 44b. Pedals 44c,44d and 44e control the state of three bistate switches, respectively,foot switch assembly left, center and right switches. In oneconfiguration of the invention the surgeon can depress pedal 44c ifirrigation, the actuation of pump 40, is desired. Pedal 44d is depressedin order to indicate which handpiece 32 or 33 the surgeon wants as theactive handpiece. Pedal 44e is actuated by the surgeon to indicate ifhe/she wants the bulb 248 associated with the active handpiece 32 or 33to be actuated. Foot switch assembly 46 is connected to control console36 by a cable 328. Cable 328 carriers conductors over which signalsgenerated by the Hall effect sensors associated with pedals 44a and 44band the signals selectively transmitted through the switches associatedwith pedals 44c, 44d and 44e are supplied to the control console 36.Cable 328 also carriers conductors connected to the NOVRAM 329 so as toenable the control console to retrieve the data stored therein.

FIG. 13 is a block diagram of the data fields contained within theNOVRAM 72 within a handpiece such as handpiece 32. NOVRAM 72 containsthree basic types of data: header data which provides basicidentification about the handpiece in which it is installed;encyclopedia data which describes the operating characteristics of thehandpiece; and custom screen data that contains instructions about anycustom images that the handpiece requires presented on display 37.

The first data presented is the header data and the first field is aheader length field 342 which provides an indicate of the portion of thememory occupied by the header data. A set of handpiece identificationfields 343, 345, and 345 follow header length field 342. Handpieceidentification fields 343-345 contain such information as the name ofthe handpiece, for example, sagittal saw, the part number for thehandpiece, the handpiece serial number, and a code identifying themanufacturer of the handpiece. A code revision field 346 contains anindication of the version of the data in the NOVRAM 72 that is beingread. A check sum field 347 contains data useful for errordetection/error correction of the data read from the handpiece. The datacontained in fields 342-347 are the header data.

The encyclopedia data follows the header data. the first field ofencyclopedia data is a table length field 348. Table length field 348contains an indication of the size of the NOVRAM 72 in which theencyclopedia is contained. Following table length field 348 is ahandpiece definition field 350). Handpiece definition field 350 containsinformation that Describes the characteristics of the handpiece. Thisinformation can include a description of: whether the handpiece is amicro duty or heavy duty handpiece; if the forward/reverse directioncontrols are convention or in reverse orientation, whether the motor isrun with or without feedback; whether the light and water accessoriescan be used with the handpiece; and the number of significant digitsthat should be presented on the image formed on display screen 37.

The next two data fields, fields 352 and 354, are device type fieldsthat identify the characteristics of devices that are installed into thehandpiece. In one version of the invention, each field 352 and 354 is afour bit field. Each one of the 16 bit combinations serves to identifywhether or not a device is present and the features of the device. Forexample, in one code scheme bit combination 00000 is used to indicate nodevice is present and combination 0001 is used to indicate the signalgenerated by the device is a main trigger (combination forward andreverse trigger). This code may be contained within NOVRAM 72 if thedevice is the described Hall effect sensor 94 (FIG. 3). In this codescheme, combination 0100 is used to indicate that the device is aninternal handpiece temperature sensor 96 (FIG. 3) and that the signalgenerated device is representative of the temperature of the handpiece.

The next 8 fields, fields 356-370, are voltage level fields that containinformation about range of signals that the devices internal to thehandpiece generate and how they control the actuation of the handpiece32. Four of the fields, fields 356-362, contain information about thesignal produced by first device, hereinafter generically referred to asdevice A. Fields 356-370 contain information about the signal producedby the second device, hereinafter referred to as device B.

The information contained in fields 356-370 are a function of the natureof the associated devices. For example if the devices are sensors thatgenerate signals represented of the user-selected operating speed of themotor and the temperature of the device, fields 356-362 and 366-370would, respectively, contain data about the motor speed signal and thethermal state of the handpiece. Table 1 below identifies the type of thedata that is potentially present in these fields.

                  TABLE 1                                                         ______________________________________                                        Data type based on device type.                                                        Device Is        Device Is                                           Data Field                                                                                 Speed Sensor            Temp. Sensor                             ______________________________________                                        356, 364 Maximum Voltage From                                                                           Voltage Representative                                                     Sensor (Voltage                                                                          Of Device Shut-Down                                                Representative of                                                                      Temperature                                                          Maximum Speed)                                         358, 366       Minimum Voltage From                                                                        Voltage Representative                                                  Sensor (Voltage                                                                          of Device Warning                                                  Representative of                                                                      Temperature                                                          Minimum Speed)                                         360, 368       Hysterises Voltage                                                                            Undefined                                                             (Voltage Above Minimum                                                        Voltage At Which Motor                                                        Is Initially Actuated)                                 ______________________________________                                    

Fields 362 and 370 contain filter value data in the event there is aneed to digital filter the signals generated by devices A and B,respectively.

It should be recognized that the foregoing description merely describedthe data contained in fields 356-370 for just two types of devices. Thedata contained in these fields may be significantly different for othertypes of devices. For example, one potential device integral with ahandpiece may by a set of buttons that represent a plurality of switchesthe physician can selectively depress. With this type of device, thedepression of a specific set of buttons would cause a unique signal tobe generated by the handpiece 32 that the control console 36 would, inturn, recognize as a specific command If these buttons form an installeddevice, the associated fields 356-362 or 364-370 could contain dataindicating the type of command a particular signal produced by thedevice represents. Two such commands for example could be commands toraise and lower the maximum speed at which the motor internal to thehandpiece can operate.

Fields 372-382 contain data regarding the coefficients used to processthe signals produced by devices in the handpiece. Fields 372-376 containdata for three coefficients used to process the signal generated bydevice A. Fields 376-382 contain data for three coefficients used toprocess the data used to process the signal generated by device B.

In general it is contemplated that the data produced by devices A or Bbe processed using the following polynomial function:

    y=ax.sup.2 +bx+c

Where:

x is the digitized version of the signal produced by device A or B

y is the result used by the downline processing modules internal to thecontrol console. It is contemplated that fields 372 and 378 contain thedata representative of coefficient "a"; fields 374 and 380 contain thedata representative of coefficient "b"; and fields 380 and 382 containthe data representative of coefficient "c". Thus, the data in fields372-382 provides coefficients for greater than first order correction ofvariations from the normal of the signals produced by the handpiecedevices that occur due to differences in the output characteristics ofthe individual devices.

Fields 384-392 contain data used to establish the operating speeds ofthe motor 52 (FIG. 2) internal to the handpiece. Field 384 contains datarepresentative of motor stall speed, the minimum speed (revolutions persecond) at which the motor 52 should operate when the signal from theassociated handpiece device A or B is at the minimum voltage level.Field 386 contains an indication of the lowest maximum speed which theuser can establish for the motor 50. This data makes it possible for themedical personnel to establish their own set point for the highestmaximum speed at which they want the motor to function, if they wishthat speed to be below the established maximum speed. Field 388 containsdata representative of the highest speed at which the motor can operate.Inferentially, the data stored in field 388 is also representative ofthe highest maximum speed set point at which the user can program thehandpiece. Field 390 contains data indicating the incremental differencein speed that the maximum speed set point of the motor can be adjusted.For example, field 390 contains data indicating whether the maximumspeed set point can be adjusted in increments of 100 RPM, 500 RPM or1000 RPM.

Fields 391 and 392 contain data that is used if the motor can beoperated in a forward-reverse oscillatory mode. Field 391 contains anindication of the lowest speed at which the motor can be operated in theoscillatory mode. Field 392 contains data representative of the maximumspeed at which the motor can be operated at when in the oscillatorymode.

Field 394 contains data about the gear ratio of the handpiece 32. Thisdata is used to calculate the true speed of the cutting attachmentcoupled to the handpiece. In the handpiece, handpiece 32, a cuttingattachment is directly coupled to the motor rotor 60. Therefore for thisparticular handpiece 32, field 398 would contain data indicating a 1:1ratio between the rotation of the motor and the rotation of the cuttingattachment. Field 396 contains data about the number of poles internalto the motor. Control console 36 uses this data to regulate theapplication of energization current to the individual poles.

Fields 398 and 400 contain data about the bias current that is appliedto the handpiece in order to energize the devices A and B internal tothe handpiece 32 or 33. Fields 398 and 400, respectively, contain dataabout the minimum and maximum bias current that is applied to thehandpiece 32 or 33,

Fields 402-404 contain data regarding the maximum current the motorshould draw when in different phases of its cycle of operation. Fields402 and 403 contain indication of the maximum current the motor shoulddraw during its initial start up cycle. More specifically, field 402contains data indicating the maximum current that should be drawn whenthe motor is in the reset phase of the start up cycle. Field 403contains an indication of the maximum current the motor should drawduring the enable phase of the start up cycle. Field 404 contains anindication of the maximum current at which the motor should perform anadjustment of the coefficient of a transfer function used to the motorshould draw during its run time.

Fields 406, 408 and 410 contain the coefficients used in an equation tocalculate the current set point based on defined torque set point. Thesecoefficients are needed, because, as explained hereinafter, the memoryalso includes an indication of the maximum torque the motor shoulddeliver for given motor speeds. While ideally the currentdrawn-to-torque generated ratio should be linear, there may be somevariation. Consequently, coefficients that used in a greater-than-firstorder equation are stored within the memory so that the control consolecan perform a relatively accurate torque-to-current conversion. In thedescribed version of the invention, three coefficients, enough forproviding the constants for a quadratic equation, are supplied.

Fields 412, 414 and 416 contain the coefficients employed during motorcontrol when the control console is engaged in current control mode ofthe motor. Fields 418, 420 and 422 contain the coefficients employedwhen the control console is engaged in the speed control mode of themotor. In both modes, the control console is engaged in proportionalintegral differential control of the motor. That is the control consolemodifies the feedback signals received by the motor in order to ensureits precise operation.

Fields 428-434 contain data representative of the torque/speed setpoints that define the safe operating range of the motor. As seen byline 436 of FIG. 14, a motor has a linear speed-to-torque ratio whereinthere is an inverted linear relationship between the maximum speed atwhich a motor can be driven and the torque the motor should be allowedto develop at that speed in an open loop drive mode. If, for a givenspeed the motor develops excess torque, the energization current appliedto the motor may cause undesirable results to occur such as ranging fromthe excessive heating of the motor to the wearing out of the componentsforming the motor.

In the integrated tool system 30 of this invention, fields 428-434contain set point data that allow the control console to internally mapa custom speed/torque plot 438 for the motor internal to the handpiece32. Fields 428, 430 and 432 each contain data indicating for a givenpercent of the maximum speed of the motor an indication of the percentof the maximum torque the motor should be allowed to develop. Forexample, field 432 may contain an indication that when the motor isoperating at 20% of its maximum speed it should develop more than 65% ofthe maximum permissible torque. The maximum speed upon which thesevalues are based is the maximum speed specified in motor maximum speedfield 388. The fourth speed/torque field, field 434, contains anindication of the maximum torque, the zero speed torque, the motor candevelop. The three other torque set points are based on the maximumtorque specified in field 434.

Line segments 439A to 439D of plot 438 depict the profile of thespeed-to-torque relation generated as a result of the plotting of theset point data in fields 428-434. Line segment 439A is extends from thefrom the speed/torque set point specified in the first, highest speedfield, field 428, to the maximum speed/zero torque set point. As can beseen by plot 438, in preferred versions of the invention, this firstspeed/torque set point is selected so that line segment 439A issubstantially vertical. Thus, when the motor is running at the maximumspeed, the surgeon has some ability to generate a torque with the motor,bear down at a surgical site, without having the motor speed drop off.

Line segments 439B, 439C and 439D of plot 438 are shallow slopeddiagonally plots. These plots are arranged so that as the torquegenerated by the motor increases the speed decreases at differing ratesof deceleration. The diagonal profile of these plots thus ensure that asthe torque generated by the motor increases the speed of the motor willslow at a rate which will be tactually sensed by the surgeon. This givesthe surgeon the opportunity to manipulate the handpiece in such as toreduce the occurs of the motor being overdriven to the point where itstalls out. In the depicted plot 438, it can be seen that the slope ofthe individual line segments is such that at lower torque limits themaximum speed decreases relatively slowly and that at the maximum torquelimit for the motor, represented by line segment 439D, the speeddecrease is set to be quite pronounced. This later affect is intended toprovide the surgeon with a sensory notice that the motor is producingthe maximum amount of torque it can develop.

With regard to plot 438 it should also be recognized that the two pointsthat define line segment 439D are the speed/torque set point datacontained in the last intermediate field, field 432 and the zerospeed/maximum torque point specified in field 434.

Field 442 contains data representative of the length of the reset,enable and delay pulses that are applied to the internal components ofthe console in order to ensure the correct start up of the motor. Thisfield may also contain data indicating the maximum rate at which themotor should be allowed to accelerate. Field 444 contains datarepresentative of the frequency of the braking signals should be appliedto the motor, the period in which the braking signals should be appliedto the motor and the braking signals that need to be applied to themotor in order to ensure its complete stopping. Field 444 may alsocontain data indicating the maximum rate at which the motor can bedecelerated. The data in fields 442 and 444, in addition to controllingthe starting and stopping of the motor are also useful in controllingits actuation when the motor is being driven in the oscillatory mode.

Field 446 contains data used to control the filtering of the currentsignal. Data used to control the filtering of the tachometer signal iscontained in field 448. A field 449 contains what is referred to as timeout data. The time out data contained in field 449 is used by thecontrol console 36 to regulate the negation of the energization signalsto the motor in the event the motor draws a current greater than that itshould be drawing at any given instant. Field 450 contains resistorcompensation data. The data in field 450 is used to establish theimpedance of the speed feedback loop internal to the control console 36.

Field 451 a warm run definition for the handpiece. The warm rundefinition represents a internal handpiece temperature at which thehandpiece would be considered running in a warm state. Field 452contains a high current data about the handpiece. If during operation ofthe handpiece, the current draw of the handpiece exceeds the levelspecified in field, the handpiece is considered to be in a high currentdraw state. As will be discussed hereinafter, the data in fields 451 and452 are used to facilitate the recordation of the operating history ofthe handpiece.

Fields 453 and 454 contain data useful for controlling any accessoryunits that may be used in conjunction with the handpiece. In one versionof the invention fields 453 and 454, contain data relevant to theoperating parameters of, respectively, the pump 40 and the bulb 248integral with the light-and-water clip 45. More particularly, field 453contains data indicating the maximum and minimum operating speeds of thepump 40 for the handpiece and the rate at which the speed of the pumpcan be incremented. Field 454 contains data indicating the maximumintensity of the bulb 248.

The data contained in fields 348-434 and 442-454 represent theencyclopedia data within NOVRAM 72.

Fields 458 and 460 represent the data fields that contain instructionsregarding the image presented on the display 37 for operation of thehandpiece 32. Field 458 is a screen type field that provides anindication of if the handpiece uses the standard image or, if not, thenumber of custom images it requires. Field 460 contains instructions forgenerating the custom images the handpiece requires. Field 460 thuscontains the custom screen data. It should be recognized that, inpractice, field 460 is both larger in size and contains more sub-fieldsthan screen type field 458.

In the described version of the invention the data contained withinfields 342-434 and 442-460 occupy approximately 500 bytes of memory andNOVRAM 72 has 2k bytes of memory. The excess memory in NOVRAM 72 makesit possible to write different versions of the data in different blockswithin the NOVRAM. The capability of the NOVRAM 72 to hold multipleversions of the data is useful if, for example, during manufacture ofthe handpiece 32 an initial effort to write the data in the NOVRAMfails. Moreover, during the useful life of the handpiece 32 it may bedesirable to provide NOVRAM 72 with new operating data. The newoperating data may be required if, as a result of maintenance testing itis determined that the operating characteristics of the handpiece havechanged.

The data stored in EEPROM 74 within handpiece 32 are now described byreference to FIG. 15. Field 466 is an odometer field. In the odometerfield 466 data representative of the total time in second and/or minutesthe motor 52 integral with the handpiece 32 has been actuated. Thisfield is updated by the control console 36 during the operation of thehandpiece 32. There is also a scheduled service field 467 in which anindication of when, in terms of total time of operation, the handpiece32 should next be subjected to a preventive maintenance inspection. Thedata in the maintenance flag field 468 is set by personnel charged withthe manufacture and maintenance of the handpiece 32.

When the handpiece 32 is attached to the control console 36, the controlconsole compares the total time the handpiece 32 has been actuated fromthe odometer field 466 to the scheduled service field 467. If, as resultof this comparison it appears that the handpiece 32 is approaching apoint in its run time cycle at which maintenance will soon be requiredor is required, the console 36 will generate an appropriate message ondisplay 37. The console 36 may also allow use of the handpiece 32 onlyif the surgeon makes it a specific acknowledgement that he/she is awarethat the time period for performing maintenance on the handpiece is pastdue. A service history field 468 contains an indication in past runtimes, of when the last three services of the handpiece occurred.

EEPROM 74 also includes a maximum temperature field 469. Maximumtemperature field 469 contains an indication of the maximum internaltemperature of the handpiece 32 as monitored by temperature sensor 96during the operation of the handpiece. When the control console 36initializes the system 30 for use with the handpiece 32, the consoleretrieves the temperature data stored in the warm run field 454. If,during the use of the handpiece 32, the temperature of the handpieceexceeds the past highest temperature, control console 36 writes the newtemperature into field 469. The data in the maximum temperature field469 is then read from EEPROM 74 during the maintenance of the handpiece32 in order to assist in the evaluation of whether or not the handpieceis operating within acceptable parameters.

EEPROM 74 also contains warm run time field 470 in which an indicationof the total time the handpiece is run at a temperature exceeding thatspecified in the warm run definition field 454 is stored. There are alsomaximum current drawn and high current run time fields 471 and 472,respectively. Maximum current drawn field contains an indication of theinstantaneous maximum current drawn by the handpiece. High current runtime field 472 is used to store an indication of the total time ofoperation for the handpiece at which it draws a current that exceedsthat specified in high current definition field 452.

The average speed at which the handpiece is run is stored in an averagespeed field 473. The total times the handpiece is plugged into a controlconsole 36 is recorded in a times coupled field 474. EEPROM 74 alsoincludes an override count field 475. Override count field 475 containsan indication of the number times a condition has arisen in which, inorder for the handpiece to be operated, an override command must beentered through the control console.

The basic structure of the control circuit internal to the controlconsole 36 is now described by reference to the block diagram formedwhen FIGS. 16A and 16B are assembled together. A main controller 492 isresponsible for overall control of the system 30. The main controller492 is the component internal to the control console 36 that reads thedata stored in the handpiece memories 72 and 74 and foot switch assemblymemory 329 and that acts on the data stored in the memories. The maincontroller 492 receives input commands from a number of sources such asthe sensor 94 that monitors hand switch 39, the foot switch pedals 44a,44b, . . . and the touch screen display 37. Based on instructionsembedded in the main controller 492, the retrieved data, the inputcommands and the signals from the sensors 94 and 96, the main controller492 controls the application of energization signals to the handpiece32, the pump 40, the intensity of the light emitted by the bulb 248integral with light-and-water clip 45 and the information that ispresented on the touch screen display 37.

The AC line voltage that is used by the control console 36 to bothenergize the handpiece 32 and the control console is initially convertedinto a 40 VDC signal by an AC-to-DC converter 494. In some preferredversions of the invention, the AC-to-DC converter 494 is a plug-inmodule that can be physically removed the body of the control console36. This makes it possible to provide AC-to-DC converters 494 withdifferent power ratings to be attached to the control console 36. Forexample, it could be possible to provide a 200 Watt Ac-to-DC converteror a 400 Watt converter depending on the power requirements of thehandpieces 32 or 33 with which the console will be used. In theseversions of the invention, the AC-to-DC converter 494 is configured toassert a POWER₋₋ SUPPLY₋₋ SENSE (PWR₋₋ SNS) signal to the maincontroller 492. The PWR₋₋ SNS signal provides the main controller 492with an indication of the power rating of the AC-To-DC converter 494.This provides the main controller 492 with information it needs todetermine if the control console 36 can supply the power required by aparticular handpiece 32 or 33 attached to the console.

A temperature sensor 495 may be fitted inside some AC-to-DC converters494. This sensor 495 could be located adjacent a critical,heat-generating part of the converter 495 such its transformer or powerdiodes. In the event the sensor 495 determines the converter 494 isoverheating as may occur if large amounts of power are drawn forextended periods of time, or in the event of a component failure, thesensor will assert a signal to the main controller 492. In some versionsof the invention, the signal asserted by temperature sensor 495 is aspecific PWR₋₋ SNS signal. Also, it may be possible to send twodifferent signals depending on the state of the sensor 495; a firstPWR₋₋ SNS signal can be sent if the converter 494 is only starting tooverheat and a second signal can be sent to indicate that theoverheating has reached a critical stage. In converters 494 that supplyrelatively low amounts of power, for example, converters that draw 200Watts or less of power, sensor 495 may not be required.

The 40 VDC is applied directly to a DC-to-DC voltage converter 496.Voltage converter 496 converts the 40 VDC signal into +12 VDC, +5 VDCand -5 VDC signals that are applied to other components of the controlconsole 36 as energization signals. The 40 VDC is distributed fromvoltage converter 496 to the other components of the control console 36over a 40 VDC rail 498. In order to minimize the complexity of theremaining block and schematic diagrams, only a few representativelocations where the +12 VDC, +5 VDC and -5 VDC signals are needed areillustrated. The 40 VDC is also distributed through voltage converter496 over a dedicated conductor as a MOTOR₋₋ POWER (MTR₋₋ PWR) signalwhich is applied to the active handpiece 32 or 33. The MOTOR₋₋ POWERsignal originates from the output terminal of a relay 500 internal tovoltage converter 496. The state of relay 500 is controlled by a signalgenerated by the main controller 492.

The data in the memories 72 and 74 internal to the handpieces 32 and 33,as well as the output signals from the sensors 94 and 96, (the devices),internal to the handpieces are supplied to the main controller 492 froma handpiece interface 502. Handpiece interface 502 is connected to theoutput terminals of the handpieces 32 and 33 through two separatehandpiece sockets 504 and 505, respectively. The signals generated bythe pedals 44a, 44b, . . . associated with the foot switch assembly 46are supplied to the main controller through a foot switch interface 506.

The application of the energization signals to the handpiece isregulated by a motor controller 508. Motor controller 508 is connectedto the main controller 492 so as to receive basic commands regarding thespeeds at which the motor internal to the handpieces 32 and 33 shouldrun and how the motor should be actuated. In response to receivingcommands from the main controller 492, the motor controller 508generates trigger commands to a motor driver and current sense circuit510. Motor driver and current sense circuit 510 performs two basicfunctions. First, in response to the trigger commands generated by themotor controller 508, it selectively applies the MOTOR₋₋ POWER signal tothe motor of the active handpiece 32 or 33. Secondly, the motor driverand current sense circuit 510 monitors the current applied to the motorof the handpiece 32. Signals representative of the sensed current aresupplied to both the main controller 492 and the motor controller 508.

A display input/output controller 512 both controls the presentation ofimages on the touch screen display 37 and the generation of systemcommands based on the depression of the switch images presented on thedisplay. The display input/output controller 512 receives the basiccommands regard the particular image that should be presented on thetouch screen display 37 from the main controller 492. Based on thosecommands, the display input/output controller 512 generates the specificbit-level commands that cause the desired image to be presented. Thedisplay input/output controller further monitors the touch screendisplay 37 to determine which of the switch images presented on thescreen have been depressed and sends that information to the maincontroller 492.

A backlight and speaker controller 514 are also connected to the maincontroller 492. The backlight and speaker controller 514 controls theintensity and contrast of a fluorescent backlight 511 associated withthe touch screen display 37 that provides the backlighting needed tomake the image presented on the display visible. The backlight andspeaker controller 514 also controls the generation of warning tones bya speaker 513. A pump controller 515 controls the application ofenergization signals to irrigation pump 40. When the pump 40 is designedas a module adapted to be fitted into control console 36, pumpcontroller 516 may be integrally attached to the module in which thepump is installed.

As seen by reference to FIGS. 17A and 17B, the main controller 492includes a microprocessor 518. In the described version of theinvention, microprocessor 518 is capable of exchanging both analog anddigital signals with the complementary components forming the controlconsole 36. One suitable microprocessor that can be employed as themicroprocessor 518 of this invention is the 80C552 manufactured byPhillips Semiconductor. Microprocessor 518 retrieves the data stored inthe memories 72 and 74 of handpieces 32 and 33 as HANDPIECE₋₋RECOGNITION (HP₋₋ REC) signals from the handpiece interface 362. Thehandpiece interface 502 also provides microprocessor 518 with thesignals generated by the devices A and B internal to the handpiece, HP₋₋DVC₋₋ A and HP₋₋ DVC₋₋ B signals, respectively, and a signalrepresentative of the current drawn by the devices internal to thehandpiece, an HP₋₋ CUR signal. Microprocessor 518 provides the handpieceinterface with an indication of which of the two handpieces 32 connectedto the control console 36 should be considered the active handpiece witha digital HP₋₋ 1/2 signal.

The data stored within memory 329 internal to the foot switch assembly46 are provided to the microprocessor 518 through foot switch interface506 as FS₋₋ REC signals. In the described version of the invention boththe HP₋₋ REC and FS₋₋ REC signals are forwarded to microprocessor 518over serial data buses. Microprocessor 518 also receives from footswitch interface 46 FOOTSWITCH₋₋ FORWARD (FS₋₋ FWD) and FOOTSWITCH₋₋REVERSE (FS₋₋ RVS) signals that are representative of the signalsgenerated as result of the depression of foot switch assembly pedals 44aand 44b, respectively.

Microprocessor 518 generates a set of signals to motor controller 508for controlling the basic production of the motor energization signals.The digital signals include: a MOTOR₋₋ ON\OFF (MTR₋₋ ON\OFF) signal thatprovides a basic control of whether or not motor controller and currentsense circuit 510 is able to generate the signals used to control theenergization of the motor; RESET (RST) and ENABLE (ENB) signals that arecycled in order to control the initial generation of the energizationsignals; a FORWARD/REVERSE (F/R) signal that regulates the sequence inwhich the energization signals should be generated; and a BRAKE (BRK)signal that is asserted whenever the microprocessor 518 determines thereis a need to generate energization signals that facilitate thedeceleration of the motor 52 in the handpiece 32. Microprocessor 518also generates an analog SPEED₋₋ SET₋₋ POINT (SPD₋₋ SP) signal to motorcontroller 508 that indicates the speed at which the motor 52 internalto the handpiece 32 is to be energized. Microprocessor 518 receivesdirectly from motor controller 518 a variable frequency digitalTACHOMETER (TACH) signal that is representative of motor speed.

Microprocessor 518 also selectively forwards to motor controller 508 aVCO signal, a MOTOR₋₋ VCO (MTR₋₋ VCO) signal, a DUTY signal and aMOTOR₋₋ DUTY (MTR₋₋ DTY) signal. These signals are asserted bymicroprocessor 518 when the control console 36 is used to be provideenergization signals to a handpiece that is operated in a direct drivemode. A handpiece is operated in the direct drive mode when theenergization signals applied thereto are not applied directly to a brushless, Hallless motor 52 such as contained within the described handpiece32. For example, direct drive mode energization signals are provided toa handpiece that is functioning as charged battery pack for a specifictype of surgical tool. Alteratively, direct drive mode energizationsignals are provided to handpieces wherein the actual tool is some typeof motorless device such as a laser or an ultrasonic tool.

The VCO and DUTY signals are the actual signals asserted bymicroprocessor 518 to regulate the direct drive energization of thehandpiece. These signals are multi-bit parallel signals. As discussedhereinafter, other components internal to the main controller 492convert these signals into analog formats for their use by motorcontroller 508. The MOTOR₋₋ VCO and MOTOR₋₋ DUTY signals are asserted tocontrol when the motor controller 508 is regulated by the VCO and DUTYsignals. The MOTOR₋₋ VCO and MOTOR₋₋ DUTY signals are one-bit signalsthat are directly forwarded by microprocessor 518 to motor controller508.

Separate HANDPIECE1₋₋ ON\OFF (HP1₋₋ ON) and HANDPIECE2₋₋ ON\OFF (HP2₋₋ON) signals are generated by the microprocessor 518 to the motor driverand current sense circuit 510. The HANDPIECEx₋₋ ON\OFF signals are usedto establish to which of the handpieces 32 or 33 the energizationsignals are applied. A RESISTOR₋₋ COMPENSATION (RES₋₋ COMP) signal isgenerated by microprocessor 518 to motor controller 508 to regulate theconfiguration of.the speed feedback loop internal to the motorcontroller 508.

Microprocessor 518 also generates PEAK₋₋ I₋₋ SET₋₋ POINT (PK₋₋ I₋₋ SP)and TIME₋₋ OFF (T₋₋ OFF) signals both of which are applied to the motorcontroller 508 to regulate the application of energization voltages tothe motor 52. The PEAK₋₋ I₋₋ SET₋₋ POINT signal represents at any giveninstant the maximum current the motor 52 is allowed to draw. The TIME₋₋OFF signal is used to establish the time out period in which theassertion of energization signals to the motor is negated after thedrawn current exceeds the limit defined by the PEAK₋₋ I₋₋ SET₋₋ POINTsignal. Both the PEAK₋₋ I₋₋ SET₋₋ POINT signal and the TIME₋₋ OUT signalare generated as multi-bit parallel signals. Other components of maincontroller 482 convert these signals into analog format signals forassertion to motor controller 508.

A two-bit GAIN signal is also generated by microprocessor 518. The GAINsignal is forwarded to the motor control and current sense circuit 510for establishing the gain of an amplifier that processes the signalrepresentative of the current drawn by the active handpiece 32 or 33.The GAIN signal, as described hereinafter, is set with the PEAK₋₋ I₋₋SET₋₋ POINT signal.

Four multi-bit parallel signals are also generated by microprocessor 518to control ancillary components of the system 30. These signals are:BRIGHTNESS (BRHTNS) and CONTRAST (CNTRST) signals that regulate thecharacteristics of the image presented on display 37; a PUMP₋₋ SET₋₋POINT signal that represents the user-selected operating speed for pump40; and a SPEAKER₋₋ OUT signal representative of a user-selected volumefor the speaker 513. The other components of main controller 492 thatconvert these signals into analog format will be hereinafter described.

Microprocessor 518 receives from motor driver and current sense circuit510 an AVERAGE₋₋ I (AVG₋₋ I) signal representative of the averagecurrent drawn by the motor 52 internal to the active handpiece 32 or 33.

Data signals representative of the images to be generated on the touchscreen display 37 and of the commands entered through the display areexchanged between microprocessor 518 and the display input/outputcontroller 512 over a communications (COMM) bus 520 (FIG. 19 A). In oneversion of the invention, communications bus 520 includes two simplexserial communications lines along with an enable line over which controlsignals regulating the writing on to and reading from the communicationlines are transmitted.

The on/off state of two of the lights that form part of the system 30are controlled directly by microprocessor 518. Microprocessgor 518generates a LIGHT₋₋ CONTROL (LGHT₋₋ CNT) signal to regulate the on/offstate and intensity of the bulb 248 mounted to the active handpiece 32or 33 through handpiece interface 502. A CCFT₋₋ ON signal that regulatesthe on/off state of the fluorescent backlight 511 associated with thetouch screen display 37 is selectively generated by the microprocessor518 to the backlight and speaker controller 514.

Microprocessor 518 both monitors the 40 VDC signal produced by AC-to-DCconverter 494 and controls the state of the relay 500 that regulates thetransmission of the 40 VDC signal as the MOTOR₋₋ POWER signal. The 40VDC signal is applied to microprocessor 518 over the 40 VDC rail 498.Normally, microprocessor 518 asserts a MOTOR₋₋ POWER₋₋ ON (PWR₋₋ ON)signal to the relay 500 to close the relay so that the 40 VDC is appliedto the motor driver and current sense circuit as the MOTOR₋₋ POWERsignal. If, however, microprocessor 518 determines that the 40 VDCeither falls below or rises above predefined tolerance limits, it willinterpret the voltage fluctuation as a fault condition. If thisdetermination is made, microprocessor 518 negates the assertion of theMOTOR₋₋ POWER₋₋ ON signal so as to prevent the application of anyenergization signals to the handpieces 32 or 33. Micrcoprocessor 518will also negate the MOTOR₋₋ POWER₋₋ ON signal if it detects any othercritical faults within the system 30.

In the illustrated version of the invention, microprocessor 518 alsoreceives from the display input/output controller a DISPLAY₋₋ TEMP(DSPLY₋₋ TMP) signal representative of the signal of the touch screendisplay 37. The DISPLAY₋₋ TEMP signal is used by the microprocessor 518to perform real time adjustments of the contrast of the display 37 inorder to compensate for changes in contrast that occur as a result ofthe fluctuations in the temperature of the display.

As shown with regard to the HP₋₋ DVC₋₋ B signal, the analog signalsreceived directly by microprocessor 518 are applied to themicroprocessor 518 through a load resistor 522. A capacitor 524 is tiedbetween the junction of the load resistor 522 and the microprocessor 518in order to filter any unusual voltage variations from the receivedsignal. Similar load resistors and filter capacitors, though notillustrated, are used to process the many, if not all, of the otheranalog signals applied to microprocessor 518.

Main controller 492 also includes a ROM-PLA 528 that is connected tomicroprocessor 518. ROM-PLA 528 stores the instructions microprocessor518 retrieves in order to determine the processing functions it is toexecute. One ROM-PLA 528 employed in control console 36 is the PSD311manufactured by WSI. ROM-PLA 528 also receives some digital inputsignals from other components forming the control console 36 andgenerates digital output signals that are processed by other componentsforming the main controller 492. The primary data and address exchangebetween microprocessor 518 and ROM-PLA is over a main processoraddress-and-data bus 530. The signals that control of the reading ofdata from and writing of data to the ROM-PLA 528 are exchanged betweenmicroprocessor 518 and the ROM-PLA over a read-write control bus 532.

In the depicted version of the invention, ROM-PLA 528 receives as inputsCABLE₋₋ A (CBL₋₋ A) and CABLE₋₋ B (CBL₋₋ B) signals that indicatewhether or not a cable 43 or 47 is attached to the sockets on the faceof the control console 36. If a cable 43 or 47 is plugged into a socket,the short circuit across the two tied together contact pins 179 (FIG.11) is detected and recognized by the main controller 492 as anindication of an attached cable.

ROM-PLA 528 receives from the handpiece interface 502 a LIGHT₋₋ SENSE(LHT₋₋ SNS) signal. This signal indicates whether or not a light clip isattached to the active handpiece 32 and, if there is, whether or not thebulb is functioning. In the depicted version of the invention, theLIGHT₋₋ SENSE signal is a two-bit signal. A PUMP₋₋ SENSE (PMP₋₋ SNS)signal is supplied to the ROM-PLA 528 from the pump controller 515whenever a pump 40 is connected to the system 30.

The PWR₋₋ SNS signal, depicted as a multi-bit signal, is supplied fromthe AC-to-DC converter to the ROM-PLA 528. The PWR₋₋ SNS signal is usedby the microprocessor 518 and the ROM-PLA 528 determine the amount ofpower the AC-to-DC converter 494 can supply. The PWR₋₋ SNS signal alsocontains an indication of temperature of the converter 494. In the eventthe PWR₋₋ SNS signal indicates that the temperature internal converter494 rises above a warning level, microprocessor 518 causes the display37 to generate a warning message, If the PWR₋₋ SNS signal indicates theconverter temperature rises above a critical level, microprocessor andROM-PLA 528 cease energization of the handpieces and causes a message togenerated to indicate the cause of the system 30 shutdown.

Microprocessor, 518 also supplies to ROM-PLA 528 over bus 530 the PEAK₋₋I₋₋ SET₋₋ POINT, TIME₋₋ OFF, DUTY, VCO, BRIGHTNESS, CONTRAST, PUMP₋₋SET₋₋ POINT and SPEAKER₋₋ OUT signals generated by the microprocessor. Aparallel-to-serial converter internal to ROM-PLA 528 converts thesesignals into digital pulses that are outputted through a single outputline.

Status signals that indicate whether or not a particular pedal 44c, 44dor 44e that is part of the foot switch assembly 46 has been depressedare supplied to the microprocessor 518 through a latch 534. The latch534 receives from the foot switch interface 506 signals FS₋₋ LFT, FS₋₋CNTR and FS₋₋ RGHT indicating whether or not a particular pedal 44c, 44dor 44e, respectively, has been depressed. The signals are supplied fromthe latch to the microprocessor 518 over the main processoraddress-and-data bus 530.

Main controller 492 further includes a dedicated digital-to-analogconverter 536 that continually generates a SPEED₋₋ SET₋₋ POINT (SPD₋₋SP) signal that is representative of the user-desired speed the motor 52internal to the active handpiece 32 or 33. Digital-to-analog converter536 is connected to the main processor address-and-data 530 bus forreceiving a digital signal from microprocessor 518 upon which theSPEED₋₋ SET₋₋ POINT signal is based. In one preferred version of theinvention, the digital signal is a 12-bit signal and theaddress-and-data bus 530 only has 8 data lines. In these versions of theinvention, the most significant 8 bits of the signal are initiallylatched into digital-to-analog converter 536 and then the remaining 4least significant bits are latched into the converter.

In the depicted version of the invention, digital-to-analog converter536 also generates an analog VREF signal which serves as a referencevoltage for other components internal to the control console 36. Thebasic reference signal produced by the digital-to-analog converter 536initially is applied to a resistor 538. The signal is then tied toground through two capacitors 542 and 544 in order to filter out anyvariations in the signal. The filtered signal is applied to thenoninverting input of an amplifier 546. The output signal from amplifier546 functions as the basic VREF signal. The VREF signal is applied asfeedback to the inverting input of amplifier 546 so that the amplifier46 functions as low impedance buffer.

The VREF signal produced by amplifier 546 is applied to the noninvertinginput of amplifier 548. The output signal from amplifier 548 is appliedto the base of an NPN transistor 549 and the collector of NPN transistor550. The collector of transistor 549 is tied to the +12 VDC voltagesource and its emitter is tied to the base of transistor 550. A VREF₋₋FS, a reference signal that is supplied to the foot switch assembly 46,is then taken off a resistor 551 also tied to the base of transistor549. The VREF₋₋ FS signal is also supplied as a feedback signal to boththe inverting input of amplifier 548 and the emitter of transistor 550.

The main controller 492 thus provides a precision, low-impedance VREF₋₋FS signal to the foot switch assembly 46 from a source that is separatefrom the source of the primary VREF signal. Amplifier 548 providesoverload protection for the VREF₋₋ FS signal. Thus, in the event thereis a short in either the foot switch assembly 46 or in the cableconnecting the foot switch assembly to the control console 36, theaffects of the short are isolated from the other components of thecontrol console.

Main controller 492 further includes two combined multiplexeddigital-to-analog converters 556 and 558. Digit-to-analog converters 556and 558 are connected to the ROM-PLA 528 to receive the pulse signalrepresentations of the PEAK₋₋ I₋₋ SET₋₋ POINT, TIME₋₋ OFF, DUTY, VCO,BRIGHTNESS, CONTRAST, PUMP₋₋ SET₋₋ POINT and SPEAKER₋₋ OUT signalsgenerated thereby and to selectively convert these signals into theiranalog equivalents. The ROM-PLA 528 connection to converters 556 and 558is over a dedicated converter bus 559. Based on the clock signalsreceived in conjunction with the pulse signals, digital-to-analogconverter 556 converts the PEAK₋₋ I₋₋ SET₋₋ POINT, TIME₋₋ OFF, DUTY, VCOsignals into their analog equivalents. Digital-to-analog converter 558converts the BRIGHTNESS, CONTRAST, PUMP₋₋ SET₋₋ POINT and SPEAKER₋₋ OUT,and PEAK₋₋ I₋₋ SET₋₋ POINT signals into their analog equivalents.

One conductor of converter bus 559 is a serial data conductor, notidentified, that serves as the conductor over which the eight digitalpulse signals are sent from ROM-PLA 528 to both converters 556 and 558.Command signals sent by ROM-PLA 528 over other conductors formingconverter bus 559 simultaneously with the pulse signals control theassertion of the individual signals produced by converters 556 and 558.

The amplitude of the analog signals generated by converters 556 and 558are set by reference to reference signals. The VREF signal produced bydigital-to-analog converter 536 serves as the reference signal uponwhich the PK₋₋ I₋₋ SP, T₋₋ OFF VCO, DUTY, PMP₋₋ SP, BRHTNS and CNTRSTsignals are based. The reference signal for the SPKR₋₋ OUT signal is aSPEAKER₋₋ FREQUENCY (SPKR₋₋ FREQ) signal that is produced by the displayinput/output controller 512. Since the volume signal produced by theanalog conversion of the volume control signal is modulated by theSPKR₋₋ FREQ signal, the resultant SPKR₋₋ OUT signal is an analog audiodrive signal that is applied, after amplification, to the speaker 513 inorder to cause the generation of the desired audio tones.

The main controller 492 also has a reset timer 560 that functions as afailsafe reset circuit. Reset timer 560 monitors the state of an addresslatch enable (ALE) signal that is transmitted from microprocessor 518 tothe ROM-PLA 528 over read-write control bus 532. In the event resettimer 560 determines the address latch enable signal remains in oneparticular state beyond a predetermined time period, the reset timerasserts a RESET₋₋ CONTROLLER (RST₋₋ CTRL) signal. The RESET₋₋ CONTROLLERsignal is forwarded to microprocessor 518, ROM-PLA 528 and to thedisplay input/output controller 512 to initiate the start of a controlconsole 36 reset sequence. In the depicted version of the invention, theRESET₋₋ CONTROLLER signal is forwarded to microprocessor 518 and allother components that respond to this signal over a branch of theread-write control bus 532.

Reset timer 560 is also tied to the rail over which the +5 VDC isdistributed. In the event the +5 VDC drops below a given value, in oneversion of the invention, +4.5 VDC, reset timer 560 will also assert theRESET₋₋ CONTROLLER signal.

FIG. 18A is a schematic diagram of the components of the handpieceinterface 502 that retrieve the data stored in the memories 72 and 74internal to the handpieces 32 and 33 and that read the signals generatedby the devices incorporated into the handpieces. A multiplexer 564connects the microprocessor 518 to the active one of the two handpieces32 connected to the control console 36. The connection established bymultiplexer 564 is determined by the state of the HP₋₋ 1/2 signal thatis asserted by microprocessor 518. Attached to the side of themultiplexer directed towards the handpieces 32 are two identical signalpaths over which the HP₋₋ RECx signals containing the stored data aresupplied to the microprocessor 518. Each signal path includes a pull-upresistor 566 that is; tied to the +5 VDC voltage source. A surgesuppressor 568, schematically represented as a reverse biased zenerdiode, is between resistor 566 and prevent excessive voltages from beingapplied to the handpiece 32 or 33.

The circuit of FIG. 18A further includes for signal paths over which thesignals from the four devices, (two devices associated with each of thetwo handpieces 32 and 33) are applied to the input terminals ofmultiplexer 564. As now can be seen by reference to the signal path overwhich the DVC₋₋ B₋₋ 1 signals, the signals generated by device B of thefirst handpiece 32, travel, each signal path includes a surge suppressor570 immediately down line of the point the signal is introduced into thesignal path. A pull down resistor 572 is tied in parallel across diode570. A resistor 574 and series connected capacitor 576 are furtherconnected in parallel between the signal path and ground to furthersignal generated by the device internal to the handpiece. The signalpath further includes a current limiting resistor 578 through which thedevice signal flow into the input terminal of the multiplexer 564. Acapacitor 580 is connected between resistor 578 and multiplexer 564 thatis tied to ground provides additional filtering of the DVC₋₋ x₋₋ xsignal. Multiplexer 564 produces three output signals: the HP₋₋ RECsignal, the HP₋₋ DVC₋₋ A signal and the HP₋₋ DVC₋₋ B signal. Thehandpiece 32 or 33 from which these signals are supplied is a functionof the HP₋₋ 1/2 signal.

FIG. 18B illustrates the components of the handpiece interface 502 thatboth supply the reference voltage to the active handpiece 32 or 33 andthat generate the HP₋₋ CUR signal. The V₋₋ REF signal produced by themain controller 492 is applied to the noninverting input of anoperational amplifier 582. A pull-up resistor 584 is tied between +12VDC voltage source and the output of the amplifier 582. The output ofthe amplifier 582 is applied directly to the base of an NPN transistor586. As will be described hereinafter, the output VREFx signal appliedto the actuated handpiece 32 or 33 is fed back to the inverting input ofamplifier 582 to ensure that it remains constant.

The emitter of transistor 586 is tied to the +12 VDC voltage supply. Thebase of transistor 586 is tied to an input terminal of a multiplexer 588through a resistor 590. Multiplexer 588 controls to which of the twohandpieces 32 or 33 the power boosted VREFx signal is supplied. In thedepicted version of the invention, the reference signal is applied tothe active handpiece 32 or 33 across two channels in the multiplexer588. This parallel routing of the reference signal is performed tominimize the effect of the internal resistance of the multiplexer 588 onthe reference signal. Two signal paths, one to each of the handpieces 32and 33, are attached to the multiplexer output ports that complement theinput terminals to which the VREF₋₋ x signal is supplied. As seen byreference to the signal path over which the VREF₋₋ 1 signal, thereference voltage to the first handpiece travels each signal pathincludes a pull down resistor 592. A surge suppressor 594 is connectedin parallel across resistor 592. The VREF₋₋ x signal is then applied tothe handpiece 32 or 33 to energize the devices internal to thehandpiece. For example, if the V₋₋ REF signal is applied to handpiece32, the signal is used as the reference signal by both the Hall effectsensor 94 and temperature sensor 96 internal to the handpiece.

A feedback line 596 is connected between nodes 595a and 595b from whichthe VREF₋₋ x signal is applied to the handpiece 32 or 33 and theinverting input of amplifier 582 so as to form a Kelvin connection.Feedback line 596 starts at the nodes, 595a or 595b on the output sideof multiplexer 588, the side of the multiplexer closest to thehandpiece. Feedback line 596 then goes back through a third channel ofmultiplexer 588 into the inverting input of amplifier 582. When thesystem 30 is in operation, amplifier 582 monitors the difference betweenthe VREF signal from the main controller 492 and the VREF₋₋ x signalapplied to the active handpiece 32 or 33. Based on this comparison,amplifier 582 drives transistor 586 to ensure that the VREF₋₋ x signalstays constant. During this signal monitoring, owing to the highimpedance of amplifier 582, the relatively low resistance to which thefeedback signal is exposed as it flows through multiplexer 588 can beignored.

Resistor 590 functions as current sensor that monitors the current drawnby the active handpiece 32 or 33 as a result of the application of theVREF₋₋ x signal. The signal present at the junction of transistor 586and resistor 590 is applied to the noninverting input of an amplifier598 through a resistor 600. A resistor 602 and a capacitor 604 areconnected in parallel between the noninverting input of amplifier 598 torespectively, divide and filter the filter the voltage presented to theamplifier. The VREF₋₋ x signal, the signal present at the junctionbetween resistor 590 and multiplexer 588, is applied to the invertinginput of amplifier 598 through a resistor 606. A resistor 608 and acapacitor 610 are connected in parallel between the output of amplifier598 and the inverting input to cause the amplifier to produce a varyingaverage signal representative of the current drawn by the devicesinternal to the active handpiece.

The output signal produced by amplifier 598 is supplied to a resistor612 wherein the signal then functions as the HP₋₋ CUR signal. A surgesuppressor 613 tied to ground clamps the HP₋₋ CUR signal to anacceptable, maximum voltage.

The output signal from amplifier 598 is also applied to reverse biasedzener diode 597. The opposed end of diode 597 is tied to the base of anNPN transistor 599. The collector of transistor 599 is tied to theoutput of amplifier 582; the emitter of the transistor is tied toground. In the event the signal produced by amplifier 598 indicates thehandpiece is drawing an excessive current, diode 597 is forced intoconduction so as to close transistor 599. The closing of transistor 599shorts the application of the VREF signal to the handpiece.

FIG. 18C is a schematic diagram of the portion of the handpieceinterface 502 that energizes and monitors the state of the bulbs 248integral with the light-and-water clips 45 that may be attached to thehandpieces 32 and 33. In the depicted system 30, the intensity of thelight illuminated by a bulb 248 is controlled by applying a pulse-widthmodulated energization signal to the bulb. Since separatelight-and-water clips 45 attached to both handpieces 32 and 33 may beprovided, handpiece interface 502 has two energization sub-circuits forselectively energizing the bulb 248 associated with each handpiece.Since the energization sub-circuits are identical, duplicate descriptionof their identical feature will hereinafter be minimized.

The bulb energization voltage is taken from the +5 VDC voltage sourcethrough a resistor 614 that is common to both energization sub-circuits.The energization signal is applied to the bulb 248 as a LIGHT₋₋ 1 signalthrough a control FET 616a capable of rapidly cycling on and off. Thecontrol FET 616a is switched by the LIGHT₋₋ CONTROL signal from themicroprocessor 618. The LIGHT₋₋ CONTROL signal is initially applied tothe base of an NPN transistor 618 through a resistor 620. The collectorof transistor 618 is tied to the +5 VDC voltage source through aresistor 622. A capacitor 624 is tied between the base of transistor622. Collectively, resistor 620 and capacitor 624 damper the slope ofthe pulse width modulated signal used to energize the bulb so as tominimize the electromagnetic interface generated by this signal.

FET 616a is a p-channel FET that is normally pulled high by the +5 VDCsignal that is applied to the gate of the FET 616a through resistors626a and 627a. The signal applied to FET 616a thus keeps the FET in theoff, non conducting, state. The output signal at the collector oftransistor 618 is used to turn on a selected one of the FETs 616a or616b. The FET 616a or 616b turned on by the collector output signal iscontrolled by a multiplexer 624. The particular FET 616a or 616b towhich the multiplexer 624 applies the signal is controlled by the HP₋₋1/2 which sets the switch state of the multiplexer. This collectoroutput signal is, for example, applied to the junction of resistors 626aand 627a so as to drive the voltage of the gate of FET 616a below thesource voltage so as to turn on the FET. The assertion of the LIGHT₋₋CONTROL signal by the microprocessor 518 thus causes the FET 616a or616b to which the signal is applied to cyclically turn on and off. Thecyclic turning on of the FET 616a or 616b causes the energizationvoltage to be applied to the associated light-and-water clip bulb 248.

The energization sub-circuits are further constructed to prevent excesscurrent from being drawn by the associated light-and-water clips 45 inthe event there is an electrical malfunction in the clips. Resistor 614has a relatively low resistance, typically under 10 ohms. A PNPtransistor 628a between resistor 614 and FET 616a so that base oftransistor 628a is tied to the resistor-source junction and thecollector of the transistor 628a is tied to the gate of the FET 616a.The emitter of transistor 628a is tied to the +5 VDC voltage source. Inthe event there is a short circuit down line from FET 616a, the voltageacross resistor 614 will rise to above the turn on level for transistor628a. The turning on of transistor 628a results in the application of anoverdrive voltage to FET 616a which causes the FET to turn off and theapplication of the energization signal to the light-and-water clip 45 tocease. This current limit circuit also prevents excess current frombeing applied to the light-and-water clip when the bulb 248 is initiallyactuated. Moreover, a surge suppressor, (not identified,) is connectedbetween FET 616a and ground.

The circuit of FIG. 18C also provides an indication of the clip/no-clipand good bulb/bad bulb state of the associated handpieces 32 and 33.These states are determined by making an inferential measurement of theresistance between the point where the signal from the handpieceinterface 502 is applied to the light-and-water clip 45 and the pointwhere the signal is returned to ground. If there is a clip 45 installedand a good bulb 248 in the clip, the resistance is approximately oneohm. If the clip 45 has a bad bulb, the resistance is approximately 400ohms. If there is no clip in place or a no bulb within the clip, thereis an infinite resistance across this circuit path.

In order to measure this resistance, an intermediate resistance,approximately 400 ohms, resistors 630a and 630b are connected from the+5 VDC voltage source and across FETs 616a and 616b. When the LIGHT₋₋CONTROL signal is not being asserted, the voltages across theseresistors are measured to provide an indication of bulb resistance,which indicates bulb state.

The measurement of the voltage across resistor 630a or 630b is made bytwo identical comparators 632a and 632b that are selectively tied to oneof the resistors through multiplexer 624. Comparators 632a and 632bcollectively produce the two-bit LIGHT₋₋ SENSE signal. Moreparticularly, the end of the selected resistor 630a or 630b distal fromthe +5 VDC voltage rail is applied to the inverting inputs of bothcomparators 632a and 632b through a resistor 634. Voltage spikes in thesignal from FET 616a or 616b are removed by a capacitor 638 tied betweenthe inverting inputs of comparators 632a and 632b and ground. Thenoninverting inputs of the comparators are tied to a voltage dividerwhich consists of series connected resistors 640, 642 and 644. Oneterminal of resistor 640 is tied to the +5 VDC and the other terminal istied to resistor 646. Resistor 644 is tied between resistor 642 andground. The noninverting input of comparator 632a is tied to thejunction of resistors 640 and 642. The noninverting input of comparator632b is tied to the junction of resistors 642 and 644.

Feedback resistors 646a and 646b are, respectively, tied between theoutputs and noninverting inputs of comparators 632a and 632b. Pull-upresistors 648a and 648b are, respectively, tied between the +5 VDCsource and the outputs of comparators 632a and 632b so as to producecause the comparators to collective produce the two-bit LIGHT₋₋ SENSEsignal. If there is no light-and-water clip 45 or no bulb 248 attachedto the selected handpiece 32 or 33, comparators 632a and 632b arepresented with an open loop-zero voltage condition. Consequently,comparators 632a and 632b combine to assert a first LIGHT₋₋ SENSE signalindicative of a no-clip/no-bulb state. If there is a clip 45 installedand the bulb is good, the low resistance of the bulb causes thecomparators to assert a second LIGHT₋₋ SENSE signal indicative ofclip-in/good-bulb state. If there is a clip installed but the bulb isbad, the higher resistance of this state over the good-bulb state willcause the comparators to assert a third LIGHT₋₋ SENSE signal indicativeof a clip-in/bad-bulb state.

The foot switch interface 506 contains components for the analogprocessing of the signals from the foot switch assembly 46 that aresimilar to those described with respect to FIG. 18A for the handpieceinterface 502. Resistors, capacitors and surge suppressors similar tothose used to process the DVC₋₋ x₋₋ x signals from the handpieces areused process the signals that result from the depression of pedals 44aand 44b so as to produce the FS₋₋ FWD and FS₋₋ RVS signals. Surgesuppressors, filter capacitors and pull-up resistors are used topreprocess the analog signals generated as a result of the depression ofpedals 44c, 44d and 44e so as to respectively produce the FS₋₋ LFT, FS₋₋CNTR and FS₋₋ RGHT signals. A circuit similar to that used to processthe HP₋₋ RECx signals is used to process the signals exchanged with thememory 329 internal to the foot switch assembly 46 in order tofacilitate the exchange of the FS₋₋ REC signals.

In some preferred versions of the invention, the VREF₋₋ FS signal is notapplied to the foot switch assembly 46 through the foot switch interface506. Instead, a dedicated conductor in the control console 36 is used toapply the VREF₋₋ FS directly to an appropriate socket opening on theface of the control console, conductor not illustrated.

The display input/output controller 512 is now described by reference toFIGS. 19A and 19B. Initially, it should be recognized that the touchscreen display 37 includes both display screen 652 and a transparenttouch screen 653 that is fitted over the display screen. The displayscreen 652 is the portion of display 37 that produces the images seen bythe surgeon. In one embodiment of this invention, display screen 652 isa liquid crystal display. A processor, integral with the displaycontrols the energization of the electrodes in the display so as tocause the desired image to appear, (processor and electrodes notillustrated). The touch screen 653 is the element of the display thatincludes the switch surfaces the surgeon selectively touches in enterinstructions and acknowledgements into the control console 36. The touchscreen 653 contains a number of transparent pressure or heat sensitiveswitches, such as variable capacitance switches, that are visuallydefined by the images presented on the display screen 652.

Display input/output controller 512 includes a display processor 654.Display processor 654 performs overall control of the images presentedon touch-screen display 37, the audio tones generated through speaker513 and the generation of commands to the main controller 492 based onthe commands entered into the console over the touch-screen display. Onesuitable processor that can be employed as the touch screen display isthe 80C31 processor manufactured by Phillips Semiconductor. Displayprocessor 654 receives basic commands regarding the images to bedisplayed and audio tones to be generated from microprocessor 518 overcommunications bus 520. In response to user-entered commands enteredfrom the touch screen 653, the display processor 654 generates commandsto microprocessor 518 and forwards them to the microprocessor 518 coverbus 520.

Display processor 654 also generates the SPEAKER₋₋ FREQUENCY signal thatis applied to converter 558 as a the speaker reference signal. TheSPEAKER₋₋ FREQUENCY signal is variable frequency pulse signal. Thefrequency of the SPEAKER₋₋ FREQUENCY serves as the basis for thefrequency of the analog audio SPEAKER₋₋ OUT signal that is selectivelyasserted by converter 558. The display processor 654 generates theappropriate SPEAKER₋₋ FREQUENCY signal based on specific command signalsreceived from microprocessor 518.

Display input/output controller 512 includes a ROM-PLA 656. One suitableROM-PLA 656 is the PSD313 marketed by Wafer Scale Integration. ROM-PLA656 contains non volatile data used by the display processor 654 tocontrol the generation of display images, the generation of audio tonesand the assertion of commands to the main controller 492. ROM-PLA 656also contains a fixed logic array that produces some of the commandsthat need to be asserted as part of the process of generating therequired images, tones and processor commands. Address and data signalsare exchanged between display processor 654 and ROM-PLA 656 over a16-bit address-and-data bus 658. The writing of data to ROM-PLA 656 andthe reading of signals from the ROM-PLA is controlled by displayprocessor 654 by the exchange of signals over a separate over aread-write control bus 660.

An EEPROM 662 is also part of the display input/output controller 512.The EEPROM stores instructional data that is required by bothmicroprocessor 518 and display processor 654 and that can change duringthe use of the control console. Such data includes a list of customconfigurations a number of doctors find useful for the procedures theyperform, the last settings of the control console 36, the last contrastvoltage supply to display 37 and the last brightness setting of thedisplay. EEPROM 662 is connected to display processor 654 overaddress-and-data bus 658. The ROM-PLA 656 controls the addressing ofdata from EEPROM 662 through the generation of signals asserted over adedicated EEPROM bus 664. Microprocessor 518 receives data from andwrites data to EEPROM 662 by exchanging basic commands and data withdisplay processor 654; based on this exchange of data, display processor654 performs the required data read or write from or to the EEPROM 662.

Display input/output controller 512 has a video controller 666 thatactually generates the commands that cause the desired video images tobe generated. One suitable video controller 666 is the E1330 controllermanufactured by Epson America. Video controller 666 generates itsspecific image formation commands based on instructions received fromthe display processor 654 over a branch of address-and-data bus 658. Thereading of data by video controller 666 is controlled by displayprocessor 654 by the assertion of commands over read-write bus 660. Theimage formation commands generated by video controller 666 are supplieddirectly to the display screen 652. The processor internal to thedisplay screen 652, based on the received commands, causes theappropriate electrodes internal to the display screen to energize so asresult in the formation of the desired image.

A bit map memory 668 is connected directly to the video image controller666. Bit map memory 668 contains sufficient memory to store multiplepages of data, each page representing a complete image that may need tobe presented on the display screen 652. Bit map memory 668 is connecteddirectly to the video image controller 666 which over a dedicated memorybus 670. The video image controller 666 uses the bit memory 668 as atemporary storage unit for holding image formation commandsrepresentative of images that are needed for presentation on the displayscreen 652. If a particular stored image is required, the instructionsfor that image ar retrieved from the bit map memory 668 by the videoimage controller 666 and forwarded by the controller 666 to the displayscreen 652.

In the described version of the system 30 of this invention, there is atemperature sensor 672 mounted to the display screen 652. Temperaturesensor 672 is used to monitor the temperature of the display screen andassert the DISPLAY₋₋ TEMP signal which is representative of the thistemperature. The DISPLAY₋₋ TEMP signal is applied to the microprocessor518. Microprocessor 518 monitors the DISPLAY₋₋ TEMP in order to makereal time adjustments of the contrast of tine image presented of thedisplay screen 652 in order to compensate for temperature inducedchanges in contrast.

The states of the switches internal to the touch screen 653 arerepeatedly evaluated by display processor 654 and ROM-PLA 656. Theswitches internal to the touch screen 653 are arranged in arow-by-column array. The ROM-PLA 656 is connected to the touch screen653 for selectively energizing a column of switches to be scanned. TheROM-PLA 656 asserts a command indicating which column is to be scannedover a dedicated column bus 674. The command asserted by the ROM-PLA 656is applied to a decoder 676. The decoder 676, in turn, energizes theselected column of switches so that the state of the individual switchestherein can be evaluated.

Once a column of switches is energized for scanning, display processor654, selectively scans each switch therein. The individual switchscanning is performed on a row-by-row basis by the display processor676. This individual switch scanning is performed by the selectivetieing of each switch row to the display processor 654 over a multi-linededicated row bus 678. The state of the signal present on each line ofthe row bus 678 serves as an indication of whether or not a switch inthe selected row-and-column position is open or closed. If the switch isclosed, display processor 654 sends the appropriate message tomicroprocessor 518 over bus 520.

The display input/output controller 512 also includes a terminal 680 tofacilitate the connection of the control console 36 to amanufacturing/maintenance computer, (not illustrated). Themanufacturing/maintenance computer provides commands to and exchangesdata with the main controller microprocessor 518 and the displayprocessor 654 over a branch of bus 520. A gate 682 connected between bus520 and terminal 680 controls the exchange of signals from with themanufacturing/maintenance computer. An enable signal that is transmittedby the display processor 654 over a conductor associated with by 520 togate 682 controls the connection of the manufacturing/maintenancecomputer to the bus 520. The connection established by bus 520, terminal680 and gate 682 make it possible for the control console to readilyreceive software updates from the manufacturing/maintenance computer andfor the console to provide the computer with information about theoperating history of the console.

The motor controller 508, now discussed by reference to FIGS. 20A and20B, determines which signal connections should be made to the windingsinternal to the motor 52 of the active handpiece 32 or 33 in order tocause the desired rotation of the motor. Motor controller 508 includes amotor control chip 686. Motor control chip 686 asserts the requisitecommand signals to the motor driver and current sense circuit 510 thatcause each winding to either be connected to receive the MOTOR₋₋ POWERsignal or tied to tied to ground. One suitable motor control chip 686that can be incorporated into control console 36 is the ML4426 chipmanufactured by Micro Linear.

One input signal into motor control chip 686 is the SPEED₋₋ SET₋₋ POINTsignal from converter 536. Motor control chip 686 uses the SPEED₋₋ SET₋₋POINT signal as a reference signal for determining the speed at whichthe handpiece motor 52 should rotate. In the depicted version of theinvention, the SPEED₋₋ SET₋₋ POINT signal is applied to motor controlchip 686 through a resistor 688. A capacitor 690 is tied between theSPEED₋₋ SET₋₋ POINT input terminal and ground in order to damp anyvoltage spikes that may be in the SPEED₋₋ SET₋₋ POINT signal.

The FORWARD/REVERSE, BRAKE, RESET and ENABLE signals asserted bymicroprocessor 518 are applied to the motor control chip 686. Motorcontrol chip 686 uses the state of the FORWARD/REVERSE signal todetermine the direction in which the handpiece motor 52 should berotated. The BRAKE signal is applied to the motor control chip 686 inorder to cause the chip 686 to assert the signals to the windingsnecessary to cause a magnetic field-induced deceleration of the rotor 56of the handpiece motor 52. The RESET and ENABLE signals are applied tothe motor control chip 686 in order to start the rotation of the motor52. Based on the state of the RESET and ENABLE signals, the motorcontrol chip 686 asserts the signals that cause the initial MOTOR₋₋POWER and ground connections to be made to the motor windings that arenecessary to accelerate the rotor 60 from the fully stopped state.

Motor control chip 686 also receives from the field coil assembly 58internal to the handpiece motor 50 three signals, W1, W2 and W3. The W1,W2 and W3 signals are the back EMF pulse signals generated by thewindings as a consequence of the rotation of the rotor 60. Once therotor 60 starts to rotate, these back EMF signals are used by the motorcontrol chip to determine when each of the windings should be connectedto receive the MOTOR₋₋ POWER signal or tied to ground. In the depictedversion of the control console, a capacitor 689 is tied between theconductor over which the individual W1, W2 or W3 signal is applied tothe motor control chip 686 and ground for filtering the back EMF pulses.A reverse biased zener diode 691 is also connected between the conductorand ground. Diode 691 provides current protection for the motor controlchip 686 in the event the associated W1, W2 or W3 back EMF signalexceeds an acceptable potential.

The motor control chip 686 is also configured to receive as an inputsignal a signal based on the PEAK₋₋ I₋₋ SET₋₋ POINT signal. Motorcontroller 508 has a comparator 692 with an inverting input to which thePEAK₋₋ I₋₋ SET₋₋ POINT signal from converter 556 is applied. The PEAK₋₋I₋₋ SET₋₋ POINT is applied to comparator 692 through a resistor 694. Acapacitor 696 is tied between the inverting input of comparator 692 andground in order to filter the PEAK₋₋ I₋₋ SET₋₋ POINT signal. A signalrepresentative of the current drawn by the windings in the handpiecemotor 52 is applied to the noninverting input of comparator 692 from themotor driver and current sense circuit 510. The output signal fromcomparator 692 is applied to the motor control chip 686. When comparator692 determines that the measured current exceeds the maximum establishedcurrent as indicated by the PEAK₋₋ I₋₋ SET₋₋ POINT signal, the outputsignal from the comparator changes state. In response to the statechange of the output signal from comparator 692, motor control chip 686stops asserting LOW₋₋ SIDE₋₋ CONTROL signals. As discussed below, theseLOW₋₋ SIDE₋₋ CONTROL signals must be asserted in order to close the loopthrough which energization signals are applied to the motor windings.

The primary output signals from the motor control chip 686 are HIGH₋₋SIDE₋₋ CONTROL (HSC) signals and LOW₋₋ SIDE₋₋ CONTROL (LSC) signals. TheHIGH₋₋ SIDE₋₋ CONTROL signals are asserted by the motor control chip 686so as to cause the motor driver and current sense circuit 510 toselectively apply the MOTOR₋₋ POWER signal to the windings. The LOW₋₋SIDE₋₋ CONTROL signals are asserted so as to cause the motor driver andcurrent sense circuit to selectively tie the windings to ground. Motorcontrol chip 686 asserts three HIGH₋₋ SIDE₋₋ and LOW₋₋ SIDE₋₋ CONTROLsignals, one pair of signals for each winding forming the motor fieldcoil assembly 58.

The three individual HIGH₋₋ SIDE₋₋ CONTROL signals, which are assertedlow, are each applied to the motor driver and current sense circuit 510through separate two-input OR gates 698. The MOTOR₋₋ ON signal frommicroprocessor 518 is applied to OR gates 698 as the second inputsthereto. The MOTOR₋₋ ON signal is also asserted low. Thus, if theMOTOR₋₋ ON signal is not asserted, a high signal will be present atleast one input into each of the OR gates 698. The high signal at theinput of OR gates 698 will cause the gates to assert high signals whichare not recognized by the motor driver and current sense circuit 510 ascontrol signals for applying the MOTOR₋₋ POWER signal to the windings.The three LOW₋₋ SIDE₋₋ CONTROL signals are applied directly to the motordriver and current sense circuit 510.

Motor control chip 686 also asserts a variable frequency DC-pulse outputsignal, not identified, that is representative of the speed of the motor52 sensed by the chip 686 as a consequence of the monitoring of the backEMF signals by the chip. This output signal is applied through aninverter 702 to a divide-by-N counter 704. The output pulses fromcounter 704 are applied to the microprocessor 518 as the TACHOMETERsignal.

A capacitor 706 is tied between one terminal, (not identified), of themotor control chip 686 and ground. Capacitor 706 serves as an externaltiming capacitor for establishing a "time-out period" during which theLOW₋₋ SIDE₋₋ CONTROL signals are negated when the current drawn by thehandpiece motor 52 exceeds the peak current set point established bymain controller 492. Normally, a current source internal to motorcontrol chip 686 provides a charge to capacitor 706. A transistorinternal to motor controller chip 686 is tied between capacitor 706 andground. This transistor is normally turned on so as to prevent capacitor706 from charging. A comparator internal to the motor controller chip686 monitors the potential across capacitor 706.

In the event the current drawn by the handpiece motor 52 exceeds thepeak current set point established by the main controller 492, motorcontroller chip stops asserting the LOW₋₋ SIDE₋₋ CONTROL signals.Simultaneously, the transistor internal to the motor control chip 686that is tied across capacitor 706 is turned off. The turning off of thetransistor internal to motor control chip 686 allows capacitor 706 tocharge. The charging of capacitor 706 causes the voltage across thecapacitor to rise above an internal reference voltage within motorcontrol chip 686. Once the voltage across capacitor 706 rises above theinternal reference voltage, the output signal from the internalcomparator undergoes a state transition so as to cause the motor controlchip 686 to start reasserting LOW₋₋ SIDE₋₋ CONTROL signals. The time-outperiod for which the motor control chip 686 negates the assertion ofLOW₋₋ SIDE₋₋ CONTROL signals is a function of the time it takescapacitor 706 to charge to the point where the voltage across thecapacitor will rise above the internal reference voltage.

In order to provide the control console 36 with the ability to vary thetime-out period in which the assertion of LOW₋₋ SIDE₋₋ CONTROL signalsare negated, a programmable current source 708 is attached to thejunction of motor control chip 686 and capacitor 706. The currentapplied to capacitor 706 by current source 708 is established by theTIME₋₋ OUT signal from converter 556.

Motor controller 508 includes a pulse width modulator control circuit(internal PWM), not illustrated, which is part of the speed controlfeedback loop for controlling the duty cycle of the chop periods asdiscussed hereinafter. The duty cycle of the chop period is controlledin order to regulate the acceleration and deceleration of the rotor 56so that the motor runs at the desired speed as indicated by the SPEED₋₋SET₋₋ POINT signal. An external impedance network in combination with anamplifier integral with the internal PWM, is provided to ensure thatthere is an accurate gain roll off for the handpiece motor 52 attachedto the control console 36 to ensure speed loop stability through therange of operation of the motor. As seen in FIGS. 20A and 20B, thisexternal network consists of a capacitor 717 and a resistor 719 that areseries connected between a PWM adjust terminal on motor control chip 686and ground. The external impedance network further includes a resistor720 and a capacitor 722 that are connected across capacitor 717 andresistor 719.

This external impedance network of the motor controller 508 of thisinvention further includes additional components that are capable ofchanging the impedance of the network. In the depicted version of theinvention, the external impedance network includes a resistor 721.Resistor 721 is connected at one end to ground and is selectively tiedto the junction of capacitor 717 and resistor 719 through a multiplexer724. Multiplexer 724 connects/disconnects resistor 721 to the externalimpedance network based on the state of the RESISTOR₋₋ COMPENSATIONsignal asserted by the main microprocessor 518.

Motor controller 508 also controls the application of direct drive modeenergization signals to a handpiece. The control console 36 is operatedin the direct drive mode by having the main controller 492 take controlof a voltage controlled oscillator (internal VCO) in motor controllerchip 686, not illustrated, and the internal PWM. The internal VCOcontrols the commutation frequency of the application of the MOTOR₋₋POWER signals to the motor windings. This commutation frequency is thebasic frequency with which the MOTOR₋₋ POWER signal is applied to theseparate windings, the time period each HIGH₋₋ SIDE₋₋ CONTROL signal isasserted. The chop cycle regulated by the internal PWM is the on-offduty cycle the winding complementary to the winding to which the MOTOR₋₋POWER signal is applied is tied to ground. Typically multiple "on" chopperiods occur during an individual commutation "on" period. Thus, duringeach period a particular HIGH₋₋ SIDE₋₋ CONTROL signal is asserted to onewinding, the LOW₋₋ SIDE₋₋ CONTROL signal that is asserted to thecomplementary winding is cycled on and off a number of times.

In the depicted motor controller 508, the internal VCO of motor controlchip 686 is normally adjusted by a capacitor 710 which is tied between aVCO adjust terminal on chip 686 and ground. A series connected resistor714 and capacitor 716 that are connected across capacitors 710 and 712also adjust the internal VCO tuning and compensation. Further adjustmentof the internal VCO is accomplished with an additional externalcapacitor 718 that is connected between the VCO adjust terminal and aramp terminal also on the chip 686.

The control console 36 is operated in the direct drive energization modeby the selective assertion of the VCO and DUTY signals to, respectively,the internal VCO and internal PWM within the motor control chip 686. TheVCO and DUTY signals are applied from converter 556 to inputs ofseparate channels of multiplexer 724. Multiplexer 724 functions a switchto control the application of VCO and DUTY signals to the motor controlchip 686. The VCO signal is selectively applied from multiplexer 724 tothe VCO adjust terminal of the motor control chip 686. The DUTY signalis selectively applied from multiplexer 724 to the PWM adjust terminalof the motor control chip 686. The application of the VCO and DUTYsignals to the motor control chip is controlled by the assertion of theMOTOR₋₋ VCO and MOTOR₋₋ DUTY signals by microprocessor 518. The MOTOR₋₋VCO and MOTOR₋₋ DUTY signals are applied to the address inputs ofmultiplexer 724 in order to establish the circuit connections made bythe multiplexer. Depending on the state of the MOTOR₋₋ VCO and MOTOR₋₋DUTY signals, none, one of or both of the VCO and DUTY signals may beapplied to the motor control chip 686. When the VCO and DUTY signals areapplied to the motor control chip 686, the chip asserts the necessaryHIGH₋₋ and LOW₋₋ SIDE₋₋ CONTROL signals to effect the desiredapplication of direct drive energization signals.

The motor driver and current sense circuit 510 is now described byinitial reference to FIG. 21. Motor driver and current sense circuit 510includes a motor driver chip 728 to which both the HIGH₋₋ and LOW₋₋SIDE₋₋ CONTROL signals from the motor control chip 686 are applied.Based on the state of the HIGH₋₋ and LOW₋₋ SIDE₋₋ CONTROL signals, themotor driver chip 728 asserts the FET driver signals employed to causethe application of the MOTOR₋₋ POWER signals to the windings or to tiethe windings to ground. One suitable chip that can be used as the motordriver chip 728 is the IR2130 manufactured by International Rectifier.

In the illustrated version of the invention, motor driver chip 728 isalso configured to assert a FAULT signal to microprocessor518(connection to microprocessor 518 not shown). Motor driver chip 728asserts the FAULT signal whenever it receives HIGH₋₋ and LOW₋₋ SIDE₋₋CONTROL signals that would cause the motor driver chip 728 to assert FETdriver signals that would result in improper MOTOR₋₋ POWER or groundconnects to the windings. The FAULT signal may be asserted, for example,if the motor driver chip 728 receives an indication it is connect onewinding to both the MOTOR₋₋ POWER signal and ground. Microprocessor 518recognizes receipt of the FAULT signal as an indication of a fault inthe application of energization signals to the motor and takesappropriate action.

Motor driver and current sense circuit 510 also includes three high sideFETs 730 each of which is series connected to a complementary low sideFET 732. Conductors 733, which supply the energization signals to theindividual windings, are connected to the source terminals of FETs 732.Each high side FET 730 serves as the switch for connecting the conductoron which the MOTOR₋₋ POWER signal is present to one of the windingsinternal to a handpiece 32 or 33. Each complementary low side FET 732serves as the switch to connect the handpiece winding to ground.

The on\off stales of FETs 730 and 732 are controlled by the FET driversignals applied to their gates from motor driver chip 728. The FETdriver signals are applied to the gates of FETs 730 through individualload resistors 734. The signals present at the drains of FETs 730 areapplied back to the motor driver chip 728 to provide a reference fordetermining the appropriate amplitude of the signals that should beprovided to the gates of the FETs 730. The signals from the drains ofthe FETs 730 are applied back to the motor driver chip 730 throughseparate resistors 736. The FET driver signals applied to the gates ofFETs 732 are applied thereto through load resistors 738.

An inductor 740 is connected between the drain of each FET 730 and theassociated FET 732-conductor 733 junction. Each inductor 740 has aninductance that is relatively small compared to the inductance of theassociated winding that is part of the motor field coil assembly 58. Forexample, in some versions of the invention each inductor 740 has aninductance of approximately 0.1 to 10 microhenrys, in more preferredversions and inductance of 0.1 to 1 microhenrys and in still morepreferred versions approximately 0.5 microhenrys.

Inductor 740 functions as a suppressor for a high current spike thatwould other wise develop during the commutation cycle when a FET 730 isturned off and the complementary FET 732 is turned on. A current spikeoccurs at this moment because, prior to the transition of the states ofthe FETs, FET 730 acts as a capacitor across which there is a 0 VDCpotential. At the time the state of the FET 732 changes, the FET 732becomes a low resistance conductor. Consequently, the voltage across FET730 rapidly charges. Owing to the low on-state resistance of FET 732,this voltage causes a relatively high current spike to flow through asense resistor 754 to ground. Inductor 740 suppresses the magnitude ofthe current spike.

Conductors 733 separate into two sets of branch conductors, conductors742 and 744. Conductors 742 extend to the first socket on the face ofthe control console 36 to which handpiece 32 is connected and conductors744 extend to the second socket to which handpiece 33 is connected.Conductors 742 are connected to the associated socket contacts, (notillustrated), through separate relays 746. The open/closed state ofrelays 746 is controlled by the HANDPIECE1₋₋ ON/OFF signal. Relays 746are configured so as to be in the open state unless the HANDPIECE1₋₋ON/OFF is asserted. Conductors 744 are connected to their associatedsocket contacts through individual relays 748. Relays 748 are closedonly when the HANDPIECE2₋₋ ON/OFF signal is asserted.

Also attached to conductors 733 are three additional branch conductors750. Conductors 750 serve as the conductors over which the W1, W2 and W3back EMF signals from the individual windings are applied to the motordriver chip 728.

As seen by reference to FIG. 21, the current sense portion of the motordriver and current sense circuit 510 includes a resistor 754 that istied between the drains of FETs 732 and ground. Resistor 754 serves asthe current measuring resistor through which the current drawn by thewindings flows for measurement. The voltage across resistor 754 ismeasured as measured as ISENSE+ and ISENSE- signals.

The ISENSE+ and ISENSE- signals are applied to the rest of the motordriver and current sense circuit which is now described by returning toFIGS. 20A and 20B. The ISENSE+ and ISENSE- signals are applied to aprogrammable amplifier 756 through resistors 758 and 760, respectively.A capacitor 761 is tied between resistors 758 and 760. Amplifier 756 canamplify the ISENSE signal by a gain of 1, 2 5 or 10. The gain with whichamplifier 756 boosts the ISENSE signal is modified is a function of theGAIN signal applied to the amplifier 756 from microprocessor 518.

The output signal from programmable amplifier 756 is applied to thenoninverting input of a fixed gain amplifier 762. A resistor 764 is tiedbetween the inverting input of amplifier 762 and ground and a resistor766 is tied between the output of amplifier 762 and the inverting input.In one version of the invention, resistors 764 and 766 are selected sothat amplifier 762 has again of 10.

The output signal from amplifier 762 is branched to two locations. Afirst location to which the output signal is branched is thenoninverting input of comparator 692 of motor controller 508. Thus, theinstantaneous amplified ISENSE signal serves as the signal against whichthe PEAK₋₋ I₋₋ SET POINT signal is compared in order to determine if theactive handpiece 32 or 33 is drawing more than the allowed amount ofcurrent. The second location to which the output signal from amplifier762 is applied is a two-pole Butterworth filter 768. Butterworth filter768 averages the amplified ISENSE signal in order to produce theAVERAGE₋₋ I signal. The AVERAGE₋₋ I signal is applied to themicroprocessor 518 as the measurement of the current drawn by the activehandpiece 32 or 33.

Any suitable CCFT controller and audio amplifier may be incorporatedinto the backlight and speaker controller 514, (controller and amplifiernot illustrated). One suitable CCFT controller that can be employed isthe LT1182CS manufactured by Linear Tech. The BRIGHTNESS and CCFT₋₋ ONsignal from the main controller 492 are typically applied directly tothe CCFT controller. The CONTRAST signal from the main controller isapplied to a balancing circuit that controls the application of contrastsignals to the display screen 652. In one version of the system 30, thebacklight and speaker controller 514 audio amplifier amplifies theSPKR₋₋ OUT signal by a gain of approximately 5 before applying thesignal to the speaker 513.

The pump controller 515 includes any suitable motor control circuit. Onesuch circuit is the UC 3823 controller manufactured by Unitrol. Pumpcontroller 515 is also configured so to serve as a connector thatsupplies the PUMP₋₋ SENSE signal to indicate whether or not a pump 40 isattached to the system 30.

FIG. 22 depicts in block diagram the primary modules stored withinROM-PLA 528 that contain the instructions that are selectively executedby microprocessor 518 during the operation of the system 30. Notdepicted is the basic operating system that performs the input/outputfunctions, handles interrupts and exceptions and performs the otheroperating chores required to make the system operate. A main module 782is the primary module. Main module 782 is the module that is firstactuated when the system 30 is initialized and the module thatselectively controls the actuation of the other modules. A NOVRAMcommunicator 784 contains the software instructions that control theretrieval of the data contained within handpiece NOVRAM 72 and thecomplementary NOVRAM within the footswitch assembly 46. An EEPROMcommunicator 786 contains the instruction used to control the reading ofdata from and the writing of data to the EEPROM 74 within the handpiece32 or 33. Communicator modules 784 and 786 are designed to retrieve andwrite data serially in accordance with the particular specifications of,respectively, the NOVRAM 72 and the EEPROM 74. Accordingly the specificdesign of the communicators 784 and 786 will not hereinafter bediscussed in any additional detail.

The ROM-PLA 528 includes three additional modules that are executed bymicroprocessor 518 so that control console 36 applies the correctenergization signals to handpiece 32 or 33. A speed set module 788contains the instructions for generating the SPEED₋₋ SET₋₋ POINT signal.A current set module 790 contains the instructions for generating theremaining primary control signals generated by microprocessor 518, suchas the PEAK₋₋ I₋₋ SET₋₋ POINT signal. A third module, a direct drivemodule 792, contains the instructions for generating the signals thatare asserted by microprocessor 518 when the control console 36 isselected to operate in the direct drive mode.

FIG. 23 provides a basic explanation of the process steps executed bymicroprocessor 518 based on the instructions contained within mainmodule 782. When control console 36 is initially actuated, a systeminitialization step 794 is initially performed. During systeminitialization step 794, microprocessor 518 as well as the othercomponents of the system are placed in an initial ready to run state.During initialization step 794, microprocessor 518 directs the displayinput/output controller 512 to present an a sign-on image 796,illustrated by FIG. 24, on display 37. Sign-on image 796 containsinitial information that there is an interest in presenting to thesystem user.

After initialization step 794 is executed, microprocessor 518 makes anevaluation to determine if the system 30 is to be placed in amaintenance mode as illustrated by step 798. Step 798 is actually amulti-step process. Initially, when the sign-on image 796 is presented,microprocessor reviews the data received from display input/outputcontroller 512 to determine if two phantom buttons 800 presented ontouch screen display 37 have been depressed. Buttons 800, which aredepicted in dashed lines, are not actually visible images that form partof the sign-on image 796. Instead, only support personnel, not surgicalpersonnel, know of the existence of these buttons. If the buttons 800are depressed, microprocessor 518 then evaluates whether or not amaintenance key with a maintenance code is attached to one of thesockets on the face of the console 36. A maintenance key is shapedsimilar to a handpiece motor housing 50 and plugs directly into a cablesocket 504 or 506 on control console 36. A NOVRAM is contained withinthe maintenance key. Microprocessor 518 reads the maintenance keyNOVRAM. If the microprocessor 518 determines that the NOVRAM within themaintenance key contains a valid code, the microprocessor exits the mainmodule and enters a maintenance module, represented by step 802,(maintenance module not identified.)

If control console 36 is not to enter the maintenance mode,microprocessor 518 proceeds to define the system as represented by step804. In step 804 microprocessor 518 reads a number of the signals thatit is presented in order to determine how the system should beconfigured. With regard to the handpieces, microprocessor first reviewsthe state of the CABLE₋₋ x signals to determine cables 43 or 47 arecoupled to the complementary sockets 504 and 506 on the face of thecontrol console 36. If a cable 43 or 47 is connected to a socket,microprocessor 518 evaluates whether or not a handpiece 32 or 33 isconnected to the end of the cable. Initially, this evaluation begins bymicroprocessor 518 asserting or negating the HP₋₋ 1/2 signal as isappropriate to connect the cable, and any handpiece attached thereto, tothe microprocessor through the handpiece interface 502. In one versionof this invention, the evaluation of whether or not a handpiece isconnected to a cable is made by evaluating the state of the HP₋₋ CURsignal. If the HP₋₋ CUR signal indicates that a current is being drawn,this state is recognized as an indication that a handpiece 32 or 33 isattached to the control console 36.

If a handpiece 32 or 33 is attached to the control console 36, as partof system definition step 804, microprocessor 518 retrieves the datacontained in the handpiece NOVRAM 72 and EEPROM 74. This data retrievalis performed with the aid of the instructions contained in the NOVRAMcommunicator and EEPROM communicator modules 784 and 786, respectively.This data is forwarded to microprocessor 518 in the form of HP₋₋ RECsignals.

System definition step 804 also includes a retrieval of the ancillarydata needed to configure the control console 36. This data includesdetermining whether or not a pump 40 and a foot switch assembly 46 areconnected to the control console 36. If microprocessor 518 determinesthat a foot switch assembly 46 is present, the microprocessor accessesthe NOVRAM communicator module 784 in order to retrieve the calibrationdata for the attached foot switch assembly 46 from its memory 329. Thisdata is retrieved by microprocessor 518 as the FS₋₋ REC signals. Also,the current user-selected settings for the ancillary components of thesystem are read. These settings include, the brightness and contrast ofthe display 37, the speed of the pump 40, the volume of the speaker 513and the intensity selection for the bulb 248 attached to light and waterclip 45. During the initial execution of the system definition step 804,these settings are retrieved from display input/output controller EEPROM662 wherein the settings from the last use of control console 36 arestored.

Once system definition step 804 is complete, microprocessor 518 executesan update system step 806. In update system step 806, microprocessor 518determines the appropriate control signals based on information receivedduring system definition step 804. With regard to the ancillarycomponents, microprocessor 518 establishes the BRIGHTNESS, CONTRAST,PUMP₋₋ SET₋₋ POINT, and SPEAKER₋₋ OUT, and CCFT₋₋ ON signals. Once theappropriate levels for these control signals are determined, the signalsthat need to be asserted are asserted, while the signals that may beneeded later are stored. For example, the BRIGHTNESS and CONTRASTsignals are immediately asserted since these signals are used to controlthe presentation of all images on display 37. The PUMP₋₋ SET₋₋ POINT andLIGHT₋₋ CONTROL signals, in contrast, are stored in the event thecomponents to which these signals are applied are to be actuated.

As part of update system step 806, microprocessor 518 makes theappropriate calculations needed to run the handpieces 32 or 33 attachedto the control console 36. These calculations include the generation ofa data table representative of the speed-to-torque plot 438 of FIG. 14.This data table is based on the data retrieved from the handpiece NOVRAM74.

Microprocessor 518 also uses the data retrieved from the time out field449 in handpiece NOVRAM 72 to generate a data table representative ofthe time out plot 808 of FIG. 25. The time out plot 808 is a graphicalrepresentation of the relationship between the measured speed of themotor 52 and the time period after the motor has drawn a current inexcess of that specified by the PEAK₋₋ I₋₋ SET₋₋ POINT for whichenergization signals should not be applied to the motor. Time out field449 contains data representative of two plot points; a first, low speedpoint and second, high speed point. As seen by reference to FIG. 25,when the motor is running at a lower speeds, the time period for whichits operation should be timed out is greater than when it is running athigher speed. As indicated by plot 808, for speeds less than the first,low speed, the time out period is the time period specified for thefirst speed. For speeds less than the second, high speed, the timeperiod is that of the second speed.

After update system step 806, microprocessor 518 performs an update userstep 810 (FIG. 23). In update user step 810, information regarding thestatus of the system 30 is presented to the user. The primary means byway system information is provided is by the presentation of a user timeimage 812 on display 37, which is now described by reference to FIG. 26.The commands to generate the individual elements forming the images aregenerated by the display input/output controller 512. Microprocessor518, during update user step 810 and during other times microprocessordisplays information, actually generates general image display commandsto the display input/output controller 512. Based on these commands,display input/output controller 512 causes the appropriate image to bepresented on the display 37.

User time image 812 includes a set of buttons, icons and data linesdepending on the particular state of the system. Along the bottom rightedge of image 812, smaller images indicate whether or not any handpiecesare connected to the complementary sockets of the control console 36. Ifhandpieces 32 or 33 are connected to both sockets, buttons 814 and 816appear indicating the presence of the handpieces. The user can thenselect one of the handpieces to be active by depressing the button 814or 816 for the associated socket. If neither button 814 and 816 aredepressed, each button has the three-dimensional profile of button 816and the handpiece symbol within the button appears white. Once a buttonis depressed, it has the flat profile of button 814 and the handpiecesymbol within the button goes black so as to collectively provide aquick visual indication of which of the two sockets has the activehandpiece. Main module 782 further includes instructions that causemicroprocessor 518 to recognize the assertion of the FS₋₋ CNTR signal asan indication to switch the active handpiece from the designed one tothe inactive one. Regardless of the means by which a handpiece isselected, microprocessor 518 negates or asserts the HP₋₋ 1/2 signal asis necessary to connect the selected handpiece to the control console 36through handpiece interface 502.

The illustrated user time image 812 also includes an auxiliary button817. Button 817 is used to indicate the presence of and control theactive state of handpieces that could be energized by the system butthat do not include the NOVRAM with handpiece data as described withreference to handpieces 32 and 33.

In the event a cable 43 or 47 with no handpiece is attached to controlconsole 36, a cable only icon 818 appears on the screen as representedby cable only image 820 now described by reference to FIG. 27.Alternatively, in some versions of the invention a socket cable-onlystate is represented as a button without a handpiece symbol therein. Ifa person depresses the cable only the button or foot switch 44d,microprocessor 518 causes a large no handpiece detected icon 822 to bepresented on display 37.

Returning to FIG. 26, it can be seen that if a button 814 or 816associated with a handpiece 32 or 33 connected to control console 36 isdepressed, other information is presented as part of user time image812. If a foot switch assembly 46 is attached to control console 36, afoot switch icon 826 is presented.

If a light and water clip 45 is attached to the selected handpiece 32 or33, and these ancillary components are compatible with the handpiece,microprocessor 518 will cause image 812 to include buttons 828 and 830indicating the availability of these features. It should be recognizedthat microprocessor 518 will only cause button 828, the light optionbutton, to be presented if the LIGHT₋₋ SENSE signal from the handpieceinterface 502 indicates that for the active handpiece the bulb 248 inlight-and-water clip 45 is in the good state. If the LIGHT₋₋ SENSEsignal indicates the bulb 248 is burned out, microprocessor 518 willinstruct display input/output controller 512 to generate an appropriatefault message on screen 37. Depression of buttons 828 and 830 will,respectively, cause bulb 248 and pump 40 to be actuated with theactuation of the handpiece to which they are coupled.

If appropriate for the handpiece, buttons 832 and 834 respectivelyprovide in indication of whether or not the handpiece can be driven inthe forward or reverse direction. Depression of one of the buttons 832and 834 will cause the button to flatten and the symbol containedtherein to darken as indicated by button 834. An option button 838 givesthe user the opportunity of switching to different screens that presentswitches that allow the user to control the ancillary components of thesystem 30. The buttons associated with the option screens allow the userto control the brightness and contrast of the images presented on thedisplay, the volume of the speaker 513, the rate at which pump 40supplies water and the intensity of the light emitted by the bulbassociated with the light-and-water clip 45. Moreover, as describedhereinafter, a special options screen allows the surgical personnel toenter a set of pre-defined system settings that are customized for aspecific procedure performed by an individual doctor.

Another feature that can be selected by initial actuation of optionsbutton 838 is the language in which information about the system 30 ispresented. In one version of the invention, at the time use is allowedto select the settings for the display 37 and speaker 513, displayinput/output controller 512 also presents a set of buttons and iconsthat allow the user to select the language in which the informationpresented on display 37 is presented.

For some handpieces, still other option features allow the user to setthe rate at which the motor internal to the handpiece accelerates ordecelerates. The fastest acceleration rate is based on data contained inNOVRAM field 442. The fastest deceleration is contained in NOVRAM datafield 444.

User time image 812 also includes a tool identification lines 839 thatprovides the name of the active handpiece 32 or 33. This name is basedon the data retrieved from handpiece identifier field in NOVRAM 72.Immediately below tool identification line 839 is maximum speedidentifier 840. Maximum speed identifier 840 is a data line thatindicates the maximum speed at which the handpiece 32 or 33 can beoperated. It should be recognized that this speed, as well as all otherspeed information presented on display 37 are "tip speeds" that is,speeds at the tip end, the driving end, of the handpiece. If there is atransmission within the handpiece, microprocessor 518 will make theappropriate speed conversion based on the data contained within gearratio field 394 of NOVRAM 72 to present tip speed to the surgicalpersonnel.

Immediately to the left of maximum speed identifier 840 are speedadjustor buttons 842. Speed adjustor buttons 842 allows the medicalpersonnel to reset the maximum speed so it can be adjusted downward fromthe actual maximum speed of the handpiece. During update system step806, microprocessor 518 will selectively adjust the maximum speed of thehandpiece subject to the limit data retrieved from fields 386, 388 and390 in handpiece NOVRAM 72. A slide bar 843 is located between speedadjustor buttons 842. Slide bar 843 provides surgical personnel with avisual indication of the extent it is further possible for them toeither increase or decrease the maximum speed of the handpiece.

Also as part of user update step 810, microprocessor 518 will generatethe appropriate signals to the display input/output controller 512 tocause controller 512 to generate the appropriate SPEAKER₋₋ FREQUENCYsignals so that speaker 513 will produce the appropriate audio tones.Alternatively, the display processor 654 internal to displayinput/output controller 512 may be configured to automatically generatethe appropriate SPEAKER₋₋ FREQUENCY signals based on the imagegeneration commands it receives from microprocessor 518. In one versionof the invention, an audio tone is generated each time a button or footswitch 44 is depressed in order to provide audio confirmation that thebutton/switch was depressed. Microprocessor 518 and display processor654 cooperate to cause the generation of other, distinct audio toneswhen either new information is presented on the display 37 and/or it isdetermined that a particular warning needs to be presented to the systemuser.

Once user update step 810 is executed, microprocessor 518 determines ifthe user has entered a command indicating user of the selected handpieceis now required, represented in FIG. 23 by motor switch on step 844. Inthis step, microprocessor 518 reviews the state of the on-off switch ofthe active handpiece, the appropriate HP₋₋ DVC₋₋ x signal, and the FS₋₋FWD and FS₋₋ RVS signals, to determine if any of these signals is aboveits hystersis level as specified by the data in the complementarymemories. If all of these signal states are below their hystersis,start, levels, microprocessor 518 returns and executes an abbreviatedform of the system definition step 804.

In the abbreviated form of step 804, microprocessor reviews the signalspresented to it to determine if the state of any of the signals haschanged. As part of this review, microprocessor 518 reads the headerdata contained in the NOVRAMs 72 of the handpieces attached to thecontrol console 36. A comparison revealing that the header data has notchanged is interpreted as an indication that the same handpieces arestill attached to the control console 36. Changes in the header data areinterpreted as an indication that a new handpiece has been attached tothe control console 36. If this latter condition exists, microprocessor518 will read the encyclopedia data for the handpiece.

As part of this abbreviated define system step, microprocessor 518 alsoreviews what, if any, changes the user has been made to the system 30.Microprocessor 518 receives information regarding these changes in theform of data messages from the display processor 654 that indicatewhich, if any, buttons presented on display 37 have been actuated. Thesechanges include adjustments of such variables as maximum tool speed,display brightness, and pump speed, the selection of a new handpiece tobe active, or the activation of device such as the light bulb 248 ofclip 45.

In the described version of the invention, main module 784 furtherinclude instructions that cause microprocessor 518 to recognize thecontinued assertion of the FS₋₋ LEFT signal as a result of thedepression of footswitch 44c as indication that the pump 40 is to beactuated regardless of the on/off state of the associated handpiece. Thecontinued assertion of the FS₋₋ RGHT signals as result of the depressionof foot switch 44e is recognized by microprocessor 518 as an indicationthat the bulb 248 is to be actuated regardless of the on/off state ofthe complementary handpiece. The short term depressions of switches 44cand 44e are recognized as simple commands to activate the pump and bulb,respectively, with the actuation of the handpiece.

After microprocessor 518 performs the abbreviated define system step804, similar abbreviated update system and update user steps 806 and810, respectively, are executed. In the abbreviated update system step806, microprocessor 518 makes the appropriate adjustments to the data itgenerates that control the other components of the system 30. Forexample, if FS₋₋ LFT signal was received for an extended period of time,microprocessor 518 will generate the appropriate PUMP₋₋ SET₋₋ POINTsignal so as to cause pump controller 515 to actuate the pump 40. In theupdate user step 810, microprocessor 508 generates the appropriatecommands to the display input/output controller 512 to cause theappropriate images regarding any changes in system state.

When microprocessor loops between steps 804, 806, 810 and 844, in otherwords no handpiece has been actuated, the system 30 is referred to asbeing in a user time mode.

If as a result of a review of the HP₋₋ DVC₋₋ x, FS₋₋ FWD and FS₋₋ RVSsignals during motor switch on step 844, microprocessor 518 determinesthat surgical personnel want a handpiece to be activated, system 30transitions from a user time mode to a run time mode. This transitionbegins with microprocessor, 518 rereading the data in handpiece EEPROM74 as represented by step 846. The reread of EEPROM 74 is necessarybecause, as will become clear hereinafter, the data contained thereinmay have been updated after the initial read of the EEPROM.

After the handpiece EEPROM 74 has been read, microprocessor 518 executesa start motor step 847. In step 847, microprocessor 518 generates theappropriate RESET and ENABLE signals to the motor controller 508 so thatcorrect HIGH ₋₋ and LOW₋₋ SIDE₋₋ CONTROL signals are asserted to causethe initial movement of the motor 52. The time periods for which thesesignals are asserted are based on the data retrieved from field 442 ofNOVRAM 74. The current drawn by motor 52 during the initial phase of itsoperation is monitored based on the current level data contained infields 402 and 403 of the NOVRAM 74.

Also as part of the start motor step 847, microprocessor 518 asserts theMOTOR₋₋ POWER₋₋ ON signal, the MTR₋₋ ON/OFF signal and places theFORWARD/REVERSE signal in the appropriate state. Microprocessor 518 alsoasserts the appropriate HPx₋₋ ON signal to close the correct relays 746or 748 internal to motor driver and current sense circuit 510. Only withthe closing of relays 746 or 748 will connections to the control consolesocket be made that will allow energization signals to be applied to thecontacts internal to the associated socket.

After start motor step 847, microprocessor 518 turns on the speed andcurrent set interrupts as represented by step 848. These interruptscause main module 782 to selectively call speed set module and currentset module 788 and 790, respectively, for execution. During the periodof time the handpiece 32 or 33 is actuated, the instructions within thespeed set module 788, the current set module 790 along with those in arun time module, not illustrated, integral with the main module 782 areexecuted by microprocessor 518. Once the interrupts are set,microprocessor 518 generates the signals to the other components ofcontrol console 36 to cause the appropriate energization signals to beprovided to the active, actuated handpiece 32 or 33.

Once the motor 52 has been initially actuated, a primary signalgenerated by microprocessor 518 is the SPEED₋₋ SET₋₋ POINT signal sincethis is the signal used by motor controller 508 to regulate motor speed.The instructions for establishing the SPEED₋₋ SET₋₋ POINT signal arecontained within speed set module 788. FIG. 28 illustrates the processsteps performed by microprocessor 518 based on the instructionscontained within this module. The initial step performed bymicroprocessor 518 is a read raw speed signal step 856. In step 856,microprocessor 518 reads the basic analog signal represented of theuser-selected speed for the handpiece. This signal may be the HP₋₋ DVC₋₋signal from the sensor 94 in the handpiece that monitors the position oflever arm 186. Alternatively this signal may be either the FS₋₋ FWD orFS₋₋ RVS switch if the surgeon depressed either foot switches 44a or44b.

Once the raw speed signal is read, in step 858 microprocessor 518produces a corrected speed signal. The corrected speed signal iscalculated using an established correction function wherein thecoefficients of the function are retrieved from the memory associatedwith the source of the speed signal. Thus, if sensor 94 is the source ofthe raw sensor signal, the coefficients in fields 372-376 of thehandpiece NOVRAM 72 are used as the coefficients of the correctionfunction. If either the FS₋₋ FWD or FS₋₋ RVS signals are used as the rawspeed signal, coefficients retrieved from foot switch assembly memory392 are used in the correction function.

The corrected speed signal is then used as a variable in a transferfunction to produced a adjusted speed signal as represented by step 860.This second compensation of the speed signal is performed in order tominimize any system error so that the resultant SPEED₋₋ SET₋₋ POINTsignal accurately indicates the surgeon desired speed for the handpiece.The relationship established by the transfer function is that when thecorrected speed signal indicates that the motor should be operating atthe highest possible speed, (either the surgeon set maximum speed or thedefault maximum speed,) then the motor should actually be running atthat speed. In one version of the invention, this transfer function is afirst order function. Initially the coefficient of this function isunity. As described hereinafter, as long as the handpiece remainsactuated, the microprocessor 518 will continually adjust the coefficientof this function.

As part of adjustment step 860, microprocessor 860 may further adjustthe SPEED₋₋ SET₋₋ POINT signal to prevent the handpiece motor 52 at arate greater than that specified by the default (NOVRAM) or use-setacceleration/deceleration rate. In order to perform this step it may benecessary for the microprocessor 518 to compare the user speed to theactual speed of the motor based on the filtered TACHOMETER signal.

The adjusted speed signal produced as a result of the application of thecorrected speed signal to the transfer function is then outputted bymicroprocessor 518 as the SPEED₋₋ SET₋₋ POINT signal. Motor controller508 then controls the assertion of the HIGH₋₋ and LOW₋₋ SIDE₋₋ CONTROLsignals based in part on the amplitude of this signal.

Microprocessor 518 then determines if the SPEED₋₋ SET₋₋ POINT signalindicates that the motor is to be operated below the )minimum, stall,speed as specified from the data retrieved field 388 of NOVRAM 72,represented by step 862. If this comparison indicates that the motor isto be operated above the stall speed, execution of speed set module 788is terminated as represented by exit step 864.

If, however, the comparison of step 860 indicates that the motor is tobe run below the stall speed, microprocessor 518 turns off the speed setand current set interrupts in a step 866. Integral with this step is thezeroing of the SPEED₋₋ SET₋₋ POINT signal. Microprocessor 518 thenasserts an appropriate set of BRAKE signals to motor controller 508 asrepresented by step 866. Motor controller 508, based on the assertion ofthe BRAKE signals, causes HIGH₋₋ and LOW₋₋ SIDE₋₋ CONTROL signals to beactuated that result in the ordered stopping of motor 52. The rate atwhich microprocessor 518 asserts the BRAKE signals is based on the dataretrieved from the brake control field 444 of NOVRAM 72.

Once the brake signals are asserted, microprocessor 518 terminatesexecution of the instructions within the speed set module 788 asrepresented by the transition to exit step 864. At this time, thecontrol console leaves the run time mode and returns to the user timemode as represented by step 889 on the flow chart of FIG. 23. The nextprocess step microprocessor then performs is the motor switch ondetermination step 844.

The above described speed set module 788 is constructed so that SPEED₋₋SET₋₋ POINT signal is recalculated and asserted before a determinationis made regarding whether or not the user-entered command indicates thatthe handpiece is to be operated above the minimum stall speed. Anadvantage of this arrangement is that it ensures prompt generation of aSPEED₋₋ SET₋₋ POINT signal that accurately represents the user-enteredspeed command. If the subsequent determination reveals that the useractually has deactuated the handpiece, the relatively short assertion ofthe low SPEED₋₋ SET₋₋ POINT signal will not adversely affect thesubsequent braking of the handpiece.

The process steps performed by microprocessor 518 based on the executionof current set module are now described by reference to FIG. 29.Initially, microprocessor 518 engages in a read step 872. In read step872 microprocessor 518 obtains the adjusted speed signal, thesurgeon-set or default maximum speed signal, the motor speed and thecurrent drawn by the motor.

It should be understood that this motor speed, as all other motor speedcalculations performed by microprocessor 518 is based on the receivedtachometer signal as filtered by the coefficient contained in tachometerfilter field 448 of the handpiece NOVRAM 72. Similarly, this and allother current drawn readings are based on the AVERAGE₋₋ I from the motordriver and current sense circuit 508 as filtered by the coefficientcontained in current filter field 446.

Once the requisite data is read, microprocessor executes a step 874 todetermine if the coefficient of the transfer function used to producethe adjusted speed signal should itself be adjusted. In step 874, afirst determination is made regarding whether or not the adjusted speedsignal indicates the user has indicated that the motor is to be operatedat it highest speed. If the user has made such a command, the currentdrawn by the motor is compared to current limit in the maximum motorcurrent field 404 of NOVRAM 72. If the drawn current is less than thedesignated maximum current, microprocessor 518 proceeds to an updatetransfer function coefficient step 876. If either of these twodeterminations are negative, step 876 is not executed.

In transfer function coefficient update step 876, the coefficient of thetransfer function used to produce the adjusted speed signal in step 860is updated. More particularly, the coefficient is revised to produce anadjusted speed signal that, assuming the corrected speed signalindicates that the motor is to be run at the maximum speed, will causethe motor to run at the maximum speed. This continual adjustment of thetransfer function coefficient serves to minimizes variations in thecontrol of the handpiece owing to the individual variations of thecontrol console 36. Since this updating occurs continually it alsocompensates for changes in component characteristics within the controlconsole 36 that occur as result of thermal changes in the controlconsole. A more detailed explanation of how this coefficient is updatedis found in U.S. Pat. No. 5,543,695, which is incorporated herein byreference.

After step 876, a set PEAK₋₋ I₋₋ SET₋₋ POINT and GAIN signals step 878is executed. In step 878, microprocessor initially determines the peakcurrent that the motor 52 should draw based on its current speed ofoperation. This determination is made by first determining the maximumtorque the motor should be drawing based on its speed. This maximumtorque is determined by reference to the data table containing therepresentation of the speed/torque plot 438 of FIG. 14. Once the maximumtorque is determined, the equivalent maximum current is calculated basedon a quadratic equation. The coefficients for this coefficient are thosecontained with torque-to-current fields 406-410 within the handpieceNOVRAM 72.

Microprocessor 518 then establishes the PEAK₋₋ I₋₋ SET-POINT and GAINsignals based on the calculated maximum current. If the motor isoperating at a relatively high speed such that it should only be drawingrelatively small current, microprocessor 518 will generate a relativelylow PEAK₋₋ I₋₋ SET₋₋ POINT signal. The complementary GAIN signal will beone that will cause programmable amplifier 756 to significantly amplifythe basic current measurement made across resistor 754. In contrast, ifthe motor is in a state where it is able to develop a relatively largetorque, draw a significant current, microprocessor 518 will set thePEAK₋₋ I₋₋ SET₋₋ POINT signal relatively high. The complementary GAINsignal is set so that there will be little, if any amplification of thebasic current signal.

Microprocessor 518 then proceeds to execute step 879 in order to set theTIME₋₋ OFF signal. This step is performed by reference to the datatables containing the representation of speed/time out plot 808 of FIG.25. Based on reference to the present speed of the motor and byreference to this data table, microprocessor determines the appropriatetime out period for the motor 52 in the event the motor draws a currentin excess of that specified by the PEAK₋₋ I₋₋ SET₋₋ POINT signal. ATIME₋₋ OUT signal representative of this period is then forwarded tomotor controller 508.

Microprocessor then executes a step 880 to establish the state of theRESISTOR₋₋ COMPENSATION signal. As discussed with respect to motorcontroller 508, resistor 721 is selectively connected to the externalimpedance network of the speed feedback control loop. The tieing ofresistor 721 to this network is a function of the speed of the handpiecemotor 52.

In one preferred version of this invention, resistor compensation field450 of handpiece NOVRAM 72 includes two speed settings for thecomplementary handpiece regarding when resistor 721 should beconnected/disconnected to the associated external impedance network. Afirst one of the speed settings indicates when the resistor should beconnected/disconnected as the motor speed is increasing. A second one ofthe speed setting indicates when the resistor should beconnected/disconnected as the motor speed is decreasing. These separatespeed settings are not typically not identical. In step 880microprocessor 518 reviews the current speed of the motor, its pastspeed and the speed settings contained in field 450. Based on thisinformation, microprocessor 518 asserts and negates the RESISTOR₋₋COMPENSATION as is appropriate. Thus, microprocessor 518 is real timeadjusts the external impedance of the speed loop compensation allowingoptimal speed loop stability of multiple speeds. This serves to enhancethe range c)f speeds over which control console 36 can hold the speedcontrol stable.

The execution of resistor compensation step 880 completes the executionof the instructions contained within current set module 790.Microprocessor then as leaves this module ;as represented by thetransition to exit step 882.

When the system 30 is in the run time mode, the run time module of mainmodule 782 is also executed. This sub-module is represented by twosteps, steps 886 and 888 depicted on the flow chart of FIG. 23. Step 886is a run time update system step. In step 886 microprocessor 518monitors signals representative of state conditions most critical to theoperation of the system 30. These signals include: the TACHOMETER signalrepresentative of motor speed; the AVERAGE₋₋ I signal; the 40 VDCsignal; the HP₋₋ CUR signal representative of the bias current drawn bythe devices internal to the actuated handpiece; any signal indicatingadjustments have been made to the user-setable motor maximum speed, andthe DISPLAY₋₋ TEMP signal indicating the temperature of display 37. Alsoduring the update system step 886 microprocessor 518 monitors thesignals of the devices internal to the actuated handpiece if thesesignals are not used to established speed control. For example, if oneof the devices is the described temperature sensor 96, the complementaryHP₋₋ DVC₋₋ x signal is monitored during the execution of step 886.

Also during step 886, microprocessor 518 responds to the monitoredsignals as appropriate. For example, if the surgeon has adjusted themaximum speed for the handpiece, the internal maximum speed setting forthe main controller 492 are made. If the DISPLAY₋₋ TEMP signal indicatesa change in display temperature, the appropriate adjustments are made tothe CONTRAST and BRIGHTNESS signals in order to maintain a constantimage on display 37.

Following step 886, microprocessor performs a run time update user step888. Initially, it should be recognized that as soon as the system 30transitions from the user time mode to the run time mode, displayinput/output controller 512 is instructed to switch from presenting theuser time image of 812 of FIG. 26 to a run time image 890 now describedwith respect to FIG. 30. Run time image 890 contains only theinformation surgeon personnel consider significant when a handpiece isactuated. In the depicted version of image 890, this information issimply the actual speed of the handpiece and the buttons required toadjust the maximum motor speed of the handpiece. As can be seen byreference to FIG. 30, image 890 has a speed presentation 892 that islarger than the maximum speed presentation 840 presented on the usertime image 812 and that occupies the substantially the width of thescreen. The increase in size of the speed presentation and theelimination of substantially all other images from display 37 minimizesthe amount of effort required to read the run time speed of thehandpiece.

During execution of the majority of the run time user update steps 888,the primary task of microprocessor 518 is to forward the appropriatecommand to the display input/output controller to cause the motor speedto be presented in real time. If other signals monitored bymicroprocessor 518 indicate other component state changes about whichthe user should be notified, other appropriate commands are sent to thedisplay input/output controller 512. For example, if a HP₋₋ DVC₋₋ xsignal indicates that a handpiece is excessively warming up,microprocessor 518 will instruct display input/output controller 512 toboth present an appropriate warning image and generate an appropriateaudio warning tone.

The processing steps performed by microprocessor 518 during return touser time mode step 889 will now be discussed in more detail. As part ofstep 890, microprocessor 518 accesses EEPROM communicator module 786 towrite into the handpiece EEPROM 74 data reflecting the new use historyof the handpiece. Microprocessor 518 also instructs display input/outputcontroller 512 to stop producing run time image 890 and return toproducing user time image 812.

Once system 30 of this invention enters the run time mode, the executionof the run time module steps 886 and 888 are the primary processingsteps executed. The execution of the instructions contained within thespeed set and current seat modules 788 and 790, respectively, occur asthe interrupt executions. It is however, most important that the SPEED₋₋SET₋₋ POINT signal be updated as frequently as possibly. Accordingly, inpreferred version of the invention, the interrupts are set so that theinstructions within speed set module 788 are called for execution every5 msec. The remaining motor control signals, the PEAK₋₋ I₋₋ SET₋₋ POINT,the GAIN, the TIME₋₋ OFF and the RES₋₋ COMP signals do not need to beupdated as frequently. Accordingly, the interrupts are set so that theinstructions within the current set point module 790 are called forexecution approximately every 50 msec. Steps 886 and 888 of the run timemodule do not have to be executed as frequently, these steps are onlycalled for execution once every 150 to 500 msec. In some preferredversions of the invention steps 886 and 888 are executed approximatelyonce every 200 msec.

In order to ensure that the above processing can all take place, in apreferred of the invention it takes approximately 2 msec to execute theinstructions contained in speed set module 788, approximately 15 msec toexecute the instructions contained in current set module 790 andapproximately 60 msec to execute steps 886 and 888 of main module.Collectively, this ensures that once every 200 msec, the SPEED₋₋ SET₋₋POINT signal is updated 40 times, the remaining motor control signalsare updated four times and the remain system control signals are updatedonce. This rapid updating of the SPEED₋₋ SET₋₋ POINT signal assures thatthe changes in the signal presented to motor controller 508 appearessentially analog.

As discussed above, one option system 30 allows surgical personnel is toretain an indication of the system settings preferred by individualsurgeons for specific medical procedures. This information is stored indisplay input/output controller EEPROM 662 and is selectively retrievedwhile the system is in the user time mode. FIG. 31 illustrates a surgeonselector image 896 that is presented on the display 37 based on thedepression of options button 838 and other appropriate buttons, notillustrated.

Surgeon selector image 896 includes scroll lines 898 that identify botha specific surgeon and a specific surgical procedure. Buttons 900 to theright of scroll lines 898 are manipulated to present a list ofsurgeons/surgical procedures stored in the system. A doctor selectbutton 902 to the left of scroll lines 898 is depressed to enter thesurgeon preferences for the indicated surgeon/procedure. Once surgeonselect button 902 is depressed, microprocessor 518, through displayprocessor 654, retrieves from EEPROM 662 the selected stored settings.

If settings for a new surgeon/procedure are to be entered, a new surgeon904 button is depressed. The depression of new surgeon button causes akeyboard to be presented on display 37 so that identifying data aboutthe surgeon/procedure can be entered. Then, at the end of the procedurethe settings established by the doctor are stored. These settings may beinitially stored as part of the return to user time step 889. Button 906is depressed to erase the record for a particular surgeon/procedure.Button 908 is depressed if there is a need to edit the surgeon/procedureidentifier.

Normally, for each surgeon with a stored procedure, after the procedureis again performed, the new settings entered by the doctor are stored.The depression of lock procedure button 910 stops this system fromengaging in this automatic rewriting of the stored settings.

The direct drive controller 792 includes the software instructionsmicroprocessor 518 requires to supply energization signals to ahandpiece operated in the direct drive mode as opposed to the abovedescribed motor drive mode. When these instructions are executed, thecommutation cycle of FETs 730 and duty cycle of FETs 732 are controlleddirectly by microprocessor, independent of any back EMF pulses receivedas Wx signals. Consequently, it is possible to include in the handpiecea transformer for converting the high voltage (40 VDC) low current (10Amp) signal produced by the control console into a lower voltage (10VDC) high current (40 Amp) signal used by some surgical tools. Suchconversion is possible by including in direct drive controller module792 instructions for appropriately regulating the chop and duty cyclesestablished by motor controller 508. The instructions in module 792would be executed based on appropriate instructional commands stored inNOVRAM 72 for the complementary handpiece.

Thus, when a handpiece is connected to the complementary control console36 of system 30 of this invention, main processor initially reads thedata stored in the handpiece NOVRAM 72 to determine if the handpiece isto be driven in the motor drive mode wherein the drive signals generatedbased on the state of feedback signals supplied from the motor, the backEMF signals, or in the direct drive mode.

If the handpiece is driven in the motor drive mode, main controller 492generates the requisite SPEED₋₋ SET₋₋ POINT, PEAK₋₋ I₋₋ SET₋₋ POINT,GAIN, RES₋₋ COMP and TIME₋₋ OUT signals the complementary sub assembliesrequire in order to ensure the proper energization signals are appliedto the windings of the motor internal to the handpiece. As long as themotor is developing less than its maximum torque for its given speed,motor controller 508 and motor driver and current sense circuit 510 willassert the correct signals to tie the windings of the motor to the +40VDC rail 498 and ground. The actual timing of these connections, isfurther regulated by when the back EMF signals from the motor arereceived. Proper speed feedback control is maintained by theRESISTOR-COMPENSATION signal regulating the impedance of the externalimpedance network connected to the speed feedback control loop.

Comparator 692 continually compares the selectively amplified ISENSEsignal to the PEAK₋₋ I₋₋ SET₋₋ POINT signal to determine if the torquedeveloped by the motor exceeds its established maximum. If thiscondition occurs, the output signal from comparator 692 changes state.Motor control chip 686 interprets the change in the state of thecomparator signal as a command to negate the assertion of LOW₋₋ SIDE₋₋CONTROL signals. The period of time in which the assertion of thesesignals is to be negated is a function of the TIME₋₋ OUT signal.

Control console 36 also monitors the internal temperature of theactuated handpiece. If this temperature exceeds a selected level, anappropriate warning message, and/or override re(quest will be presentedon display 37.

The surgical tool system 30 of this invention is configured so that theinformation regarding the operating parameters of each handpiece isstored within memories 72 and 74 internal to the handpiece. When thesystem is initialized, the control console 36 reads this data andconfigures itself to supply the appropriate energization signals to thehandpiece. Thus, the system 30 of this invention makes it possible toprovide a single control console 36 that can be used to provideenergization signals to handpieces with motors that rotate at speeds aslow as 10 RPM to speeds as high as 100,000 RPM and that have powerrequirements that range from as low as 20 Watts to as high as 500 Watts.(This upper limit assumes an appropriate power supply module 494 isattached.) The ability to provide a single control console that can beused to energize such a wide range of instruments eliminates the costand surgical suite clutter required with having to provide the multipleconsoles.

The control console 36 is also configured to not only supply theenergization signals required to actuate a motor internal to ahandpiece, it can supply direct drive energization signals to ahandpiece. This further increases the number and kind of handpieces thatcan be incorporated into this system 30 so as to further reduce thenumber of additional control consoles that need to be provided

Moreover, the control console 36, by reading the memories 72 and 74internal to the handpiece, automatically establishes limits regardingthe maximum speed at which the handpiece motor should be driven and thecurrent that can be drawn by the handpiece. This eliminates thepossibility that, as a result of human error, the control console 36could be configured so as to result in the application of energizationsignals that cause the motor to be overdriven or that would allow thehandpiece to draw excessive current. Both of the situations couldpotential cause inadvertent injury to the patient or the hands of thesurgeon working with the handpiece.

Still another feature of the system of this invention is that it allowseach handpiece to be readily combined with accessory units. A handpiececan, for example be easily fitted with a hand switch 39 and/or alight-and-water clip 45. Both these accessories are completely removablefrom the handpiece; the handpiece does not have any mounting tabs f:orfacilitating accessory attachment. Thus, a single handpiece can be usedboth by personnel that prefer using a smooth, cylindrical tool and bypersonnel who prefer working with the accessory attachments. Thisfeature of the invention serves to eliminates the need to providedifferent handpieces to accommodate the personnel preferences of thesurgeons working with the handpiece. This elimination in the need toprovide handpieces with different accessories permanently attachedthereto further serves to reduce the cost of outfitting a surgicalsuite.

Furthermore, the removable hand switch 39 of this invention is designedso that slip ring 184 prevents the switch from being fitted over therear of a handpiece 32 when a cable 43 is coupled thereto. Tab 196integral with slip ring 184 is dimensioned to prevent the hand switch 39from being slipped over the forward end of the handpiece 32. Thesefeatures of the invention thus prevent the hand switch 39 from beingfitted to a handpiece while a cable 43 is attached thereto. The cable 43must be disconnected from the handpiece 32. Thus, if during the processof attaching the hand switch 39, magnet 190 inadvertently comes withinclose proximity to Hall effect sensor 94, since the handpiece 32 isdisconnected from the control console 36, accidental actuation of thehandpiece is prevented. In order for the system 30 to operate, the cable43 must be properly coupled to the handpiece. In order for cable 43 tobe so coupled, tab 196 must be seated in complementary slot 185. Thesefeatures ensure that the hand switch 39 will not fall out of alignmentwith the handpiece 32 once the system is properly configured.

Moreover, in this invention, the data regarding the characteristics ofthe output signals asserted by the on/off/speed Hall effect sensors ineach handpiece is stored within the handpiece. This makes it possible touse each handpiece with different removable hand switches 39 since thecontrol console 36 can make the necessary signal processing adjustmentsto adjust for deviations in the magnetic flux of the hand switch magnets190.

Similarly, the instillation of the memory 329 in the foot switchassembly 46 allows the foot switch assemblies and control consoles 36 tolikewise be interchanged.

Still another feature of this invention is that the handpieces can beprovided with internal temperature sensors and the NOVRAMs 72 internalto the handpieces contain data regarding the acceptable operatingtemperatures for the handpieces. This makes it possible to configure thesystem so that in the event the operating temperature for any of thehandpieces exceeds the normal temperature for that specific handpiece,the console will provide a warning statement, reduce the power appliedto the handpiece and/or deactivate the handpiece if it becomesexcessively warm. This feature of the invention ensures that, if due touse or malfunction, a handpiece becomes excessively heated, there willbe little possibility that it will burn the hands of the person holdingit. Moreover, as described with respect to handpiece 32, it is possibleto provide handpieces of this invention so that the there is arelatively short thermally conductive path between temperature sensor 96and the windings 58 and front bearing assembly 64 For example, in someversions of the invention temperature sensor 96 is less than 100 milsfor windings 58 and more preferably only approximately 20 to 50 milsfrom the windings. Temperature sensor 96 is likewise less than 500 milsfrom front bearing assembly 64 and more preferably less than 300 to 400mils from the bearing assembly. In the event the handpiece 32 is droppedthis front bearing assembly 64 may go out of alignment even though suchfailure is not readily detectable by the operation of the handpiece. Asa consequence of this or other failures, windings 58 may rapidly heat.When this bearing assembly is so out of align, the actuation of thehandpiece will, however, result in the significant generation of heal:by the windings 58 and/or bearing assembly 64. Owing to the relativelyclose placement of the temperature sensor 96 to the windings 58 andbearing assembly 64 the sensor will provide a prompt indication tothrough the control console display 37 that the handpiece isoverheating. This will give the personnel using the handpiece someindication of the malfunction before excessive, injury or componentfailure inducing heat is generated.

The EEPROM 74 internal to the handpiece provides an indication of thetotal time the handpiece has been actuated. Having the ability to easilyobtain this information makes it easy for personnel charged with themaintenance of the handpiece to determine if the handpiece needs to besubjected to a maintenance inspection. The information in EEPROM 74 canalso be used by the manufacturer of the handpiece as the basis fordetermining if a particular handpiece is still under warranty.

The ability of the EEPROM 74 to store data regarding the maximuminternal temperature of the handpiece, the highest current drawn by thehandpiece and the total power consumed by the handpiece is also usefulto persons charged with the maintenance of the handpiece for determiningwhether or not the handpiece is functioning normally.

The control console 36 of the system 30 of the invention does more thanjust regulate the operation of handpiece having different energizationsignal requirements. The control console is further configured toprovided integrated control of the accessories, an irrigation pump 40and an illuminating bulb 248 that are often used in conjunction with asurgical tool. This integrated control eliminates the need to provide anadditional controller in the surgical suite.

Still another feature of the control console 36 of this invention isthat has three safety switches to prevent power from unintentionallybeing applied to a handpiece. For the MOTOR₋₋ POWER energization signalsto be applied from the AC-to-DC converter 494 to a handpiece port, firstthe MOTOR₋₋ POWER₋₋ ON signal must be asserted by microprocessor 518.Then, the MOTOR₋₋ ON signal must be asserted by the microprocessor 518to avoid the default negation of the HIGH₋₋ SIDE₋₋ CONTROL signals by ORgates 698. Finally, even if the FETs 728 are switched on, the MOTOR₋₋POWER signals will only be applied to a handpiece socket if theassociated relays 7416 or 748 are closed by the assertion of therequisite HPx₋₋ ON signal. This redundancy substantially eliminates thepossibility that the control console 36 will inadvertently apply theMOTOR₋₋ POWER energization signals to a handpiece.

Still another feature of this invention is that the inductors 740substantially reduce the magnitude of the current drawn by the FETs 732as a result of the state transition of FETs 730 and 730. The reductionof this current draw eliminates the need to provide filters in thecurrent sense portion of the motor driver and current sense circuit 510or software filters in the main controller 492 to compensate for theapparent excessive current draw that would other wise be measured by thecurrent sense circuit.

The control console 36 of the system 30 of this invention is furtherconfigured so that the post-excess current drawn time-out period duringwhich the assertion of energization signals to the handpiece is negatedis set as part of the process of configuring the control console for usewith a handpieces The ability of the motor controller 508 to make thisadjustment further enhances the ability to use the control console 36with handpieces that have different power operating requirements.

Still another feature of this invention is that control console 36allows a surgeon to rapidly alternate between using a first handpieceand a second handpiece. This facilitates the rapid as possiblecompletion of the surgical procedure. By being able to perform thesurgical procedure as quickly as possible, the amount of time thesurgical site is open to infection and the patient must be keptanesthetized is likewise lessened. System 30 of this invention also makeit possible for the surgeon to set the rates at which the handpiecemotor 52 accelerates or decelerates.

It should be recognized that the foregoing description is directed to aspecific embodiment of this invention. It will be apparent, however,from the description of the invention that it can be practiced usingalternative components other than what has been specifically described.For example, it is clearly not always necessary to provide a handpiecewith EEPROM for storing data about events that occur during theoperating life of the handpiece. Similarly, it may not always benecessary to provide the non volatile memory internal to the handpiecewith all the data provided in the described version of the invention.For example, in some versions of the invention it may be necessary toprovide only a minimal amount of data regarding the maximum speed atwhich the handpiece motor can operate and the maximum current the motorshould draw. Alternatively, in some versions of the invention it may bedesirable to provide the handpiece memory with data different from whathas been described.

For example, as illustrated by FIG. 32, handpiece NOVRAM 72 may beprovided with a set of accessory head fields 920. These Fields 920 areprovided in a handpiece to which it is necessary to attach acomplementary accessory head. This accessory head contains gears and atransmission mechanism necessary for transferring the motive powerproduced by the motor internal to the handpiece into a form in which itcan be used by a cutting accessory attached to the accessory head.Typically these gears reduce the rotational rate of the motor forapplication to the cutting attachment.

As represented by the first accessory head field 920, each of thesefields is composed of a number of sub fields. The first sub field is anaccessory head name field 922 that identifies the specific accessoryhead. The second field is a ratio field 924. Ratio field 924, like gearratio field 398 indicates the gear ratio for the particular accessoryhead. A maximum speed field 925 contains information regarding themaximum speed at which the tip of the accessory held can be driven. Anincrement field 926 contains an indication of the rate at which theuser-set maximum speed of the accessory head can be driven. There isalso an current limit field 928. Current limit field 928 contains dataindicating a correlation between the maximum current the handpiece candraw and the maximum current the accessory head can draw. Typicallyfield 928 contains an indication of the percent of the maximum torquethe handpiece can develop, (the current the handpiece can draw). Thereis also a current shut-off field 930. Current shut-off field 930contains an indication of the maximum current the handpiece with theparticular accessory head attached can draw. If the AVERAGE₋₋ I signalindicates the current drawn by the handpiece exceeds the amountspecified in current shut-off field 930, microprocessor 518, preventsthe further application of energization signals to the handpiece, insome cases by requiring a cold start of the handpiece.

In this version of the invention, during the initial system definitionstep 804, microprocessor 518 reads the handpiece NOVRAM 72 to determineif it contains any accessory head fields 922. If these fields areabsent, microprocessor 518 proceeds to initialize the system 30 asdescribed. If accessory head fields 922 are present, microprocessor !518instructs display input/output controller 512 to present the retrievednames from the individual accessory head name fields 922 on the initialuser time image 812. These names are presented below tool identificationline 839 as actuatable buttons. The surgeon using the system is thenrequired to press then appropriate name button to identify the accessoryhead that is attached to the handpiece. Main controller 492 thenregulates the application of energization signals to the handpiece basedon the remain data contained in the accessory head sub-fields 924-930for the selected accessory head.

System 30 may further be configured to provide different,user-selectable control options. For example it may be desirable toconfigure the system so that the user can first established a fixedspeed for the handpiece. Then, the depression of either the hand switchor foot pedal will cause the motor to operate only at the established,fixed speed. Alternatively, it may be desirable to give the option ofallowing surgical personnel to reset the hand switch or foot switchcontrolling the motor from functioning as contact switches that requireconstant depression in order for the motor to be actuated to single pullswitches that can be pressed once to turn the motor on and a second timeto turn the motor off.

It should similarly be recognized that the devices installed in ahandpiece may be different than what have been described. For example,if a particular handpiece is cauterizing tool, it may be desirable toprovide a remote sensor internal to the handpiece that can measure thetemperature of the surgical site to which the tool is applied.Similarly, this tool may also be provided with a second temperaturesensor that monitors the internal temperature of the tool. In a similarcontext, it should also be recognized that other handpieces may beprovided with none, one, three or more devices each of which assert asignal that is monitored by the control console.

Also, while one specific construction was described, other handpiecescould have different structures without departing from the nature ofthis invention. It may, be desirable to provide to circuit planes insidethe handpiece. A first one of the circuit planes could provide theconductive paths to the devices and power consuming members inside thehandpiece while the second plane could provide the conductive paths to aremovable memory module.

In the described version of the invention the motors 52 internal to thehandpieces were described as three-winding brush less, Hapless DCmotors. It should be recognized that in other versions of the inventionhandpieces with different motors may be provided. In these versions ofthe invention, the motor control and motor drive portions of the controlconsole 36 would be appropriately reconfigured to provide the necessaryenergization signals to the handpieces. Alternatively, it may bedesirable to provide a control console 36 with different motorcontrollers and motor drivers so that it can be used to provide thedifferent types of energization signals required by differenthandpieces. Similarly, it is contemplated that different power convertermodules 494 can be provided to facilitate the use the surgical toolsystem 30 of this invention with line voltages of different countries.

As discussed above with regard to the ability of the control console 36to provide direct drive energization signals, it should be further berecognized that not all handpieces may have direct driven motorsinternal therewith. The system may be configured so that the controlconsole substitutes as battery pack for a handpiece. Alternatively ahandpiece may be some type of device such as a laser or ultrasonicgenerator or sensor that does not have an internal motor.

It should also be recognized that the control console 36 may have adifferent configuration that what has been described. For example, someversions of the invention may have parallel or multiple microprocessorsthat perform the functions of both the main controller 492 and the motorcontroller 508. Similarly, it may not be necessary to provide theprocessor internal to the control console 36 with the software toolsemployed in the described version of the invention. Furthermore, whileone particular timing sequence for executing software tools during theactuation of a handpiece was disclosed, in other versions of theinvention tool execution may occur at a different rate. For example, itmay in some versions of the invention be necessary to execute thesoftware tool that determines if a desired current it being drawn moreoften than other software tool. Also, the algorithms employed may varyfrom what has been described.

Moreover, while in the described version of the invention, the controlconsole is described as having a power supply 494 for converting linevoltage into voltages useful for energizing components internal to thecontrol console and useful for application to the complementaryhandpiece, this module may not always be required. It may be possible toprovide the control console with a battery pack capable of supplying thepower required for energization of the control components and thehandpiece. In these versions of the invention, in order to reducecontrol console size and internal console power draw, the touch screendisplay and other components such as the pump may be eliminated.

It should also be recognized that the control console 36 can be providedwith additional components and/or process instructions so that in,addition to be used with handpieces 32 or 33 provided with NOVRAMs 72containing data regarding their operating characteristics, it can alsocan be used with handpieces without such memories. To provide suchcontrol it may be necessary to provide one or more additional sockets505 (FIG. 1) on the face of the console 36 to provide for the cablesused with these handpieces. In such a system, main controller 492 isfurther provided with an additional software module that contains theinstructions for providing energization signals to this handpiece.Button 817 presented with user time image 812 (FIG. 26) illustrates oneway of selecting this handpiece to be the active handpiece.

It should likewise be understood that the disclosed process stepsperformed by main controller 492 represent only a single set of suchsteps that can be performed in one version of this invention. Forexample, in the described version of the invention, main controller 492has bee described as basically reading the available data and thenasserting or adjusting the associated output signals. This may notalways be required. In some versions of the invention, main processormay read some data and immediately act on it. For example, the systemcould, upon reading the desired pump setting, immediately readjust thecomplementary PUMP₋₋ SET₋₋ POINT.

Similarly, the sequence and timing of the processing steps may bedifferent from what has been described. For with the describedhandpieces the SPEED₋₋ SET₋₋ POINT signals is that is most frequentlyupdated, there may be some systems or some handpieces for which that isnot always the situation. Thus, for some surgical procedures the speedof the handpiece may not be the most critical factor but the torque itdevelops, the current it draws, may be. For these system/handpieces, thePEAK₋₋ I₋₋ SET₋₋ POINT signal or a CURRENT₋₋ SET₋₋ POINT signal may bethe signal that is most often reset by the main controller 492.

Moreover, some preferred versions of the invention are furtherconfigured so that if two handpieces, both with hand switches 39attached to control console 36, and one hand switch is depressed, thecontrol console will automatically designated the associated handpieceas the active, actuated handpiece. If both hand switches 39 aredepressed, the first one to send a signal to the console 36 locks outthe switch signal from the other handpiece. In these versions of theinvention microprocessor 518 is configured so that when in the user timemode, it cycles the HP₋₋ 1/2 to periodically pole the HP₋₋ DVC₋₋ x₋₋ xsignals that could potentially generate the switch signals. The controlconsole 36 typically does not present any message to the user on display37 to indicate that this poling is occurring.

It should likewise be recognized that the images presented on thedisplay 37 can vary from what has been described. As previouslydiscussed, the handpiece NOVRAM 72 can store data regarding any customimage that needs to be presented during its operation. Alternatively,user time and run time images only slightly different from what has beenillustrated may be presented. For example, for some handpieces it may bedesirable to prevent a graphical indication of the speed at which thehandpiece is operating. This presentation may also be a matter ofphysician preference. For still other handpieces, it may be desirable oroptional to, in addition to presenting an indication of handpiece speed,further present an indication of the torque developed by the handpiece.For both these options, it is still anticipated that the run time imagespresenting this information will be larger in size than the initialimage presented as the user time image.

Therefore, it is an object of the appended claims to cover all suchmodifications and variations as come within the true spirit and, scopeof the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A surgical handpiece,said surgical handpiece including:a housing having opposed front andrear ends; an electrical power consuming unit located within saidhousing, said power consuming unit being configured to receiveenergization signals; a surgical attachment designed for application toa surgical site that is connected to said power consuming unit foractuation by said power consuming unit; a removable switch assembly,said switch assembly including a collar adapted to be releasable fittedto said housing and a switch lever movably secured to said collar; and asensor disposed in said housing, said sensor configured to generate asensor signal representative of the position of said switch lever ofsaid switch assembly relative to said sensor.
 2. The surgical handpieceof claim 1, further including a tab formed integrally with said collarof said switch assembly, said tab positioned to prevent said collar frombeing fitted over said front end of said housing.
 3. The surgicalhandpiece of claim 1, wherein said switch lever is pivotally mounted tosaid collar so that one end of said switch lever will move towards andaway from said housing.
 4. The surgical handpiece of claim 1, wherein: amagnet is disposed in said switch lever of said switch assembly and saidsensor is configured to monitor magnetic fields produced by said magnet.5. The surgical handpiece of claim 1, wherein said electrical powerconsuming unit is a motor.
 6. A powered surgical tool system, saidsystem including:a powered surgical handpiece for actuating anattachment, said handpiece having a variable speed motor for actuatingthe attachment, wherein said motor is actuated by an energizationsignal; a manually actuatable switch for regulating the speed of saidmotor, said switch generating a control signal; a non-volatile memoryintegral with said handpiece, said memory containing data representativeof the maximum current for said motor at a plurality of differentspeeds; and a control console connected to said handpiece for applyingenergization signals to said motor and connected to said memory forreading the data from said memory, said control console being configuredto:monitor the speed of said motor; monitor the current drawn by saidmotor; apply the energization signals to said motor based on the controlsignal and the speed of said motor; calculate a maximum allowed currentto be drawn by said motor based on the speed of said motor and the datain said memory representative of the maximum current for said motor at aplurality of speeds; compare the current drawn by said motor to themaximum allowed current; and when the comparison of the current drawn bythe motor to maximum allowed current indicates said motor is drawingmore current than the maximum allowed current, modulating theapplication of energization signals to said motor.
 7. The poweredsurgical tool system of claim 6, wherein:said memory includes a firstset of data fields that contain data indicating the maximum torque ofsaid motor for a plurality of different motor speeds and a second set ofdata fields that contain the coefficients of a torque-to-currentrelationship for said motor; and said control console is configured tocalculate the maximum allowed current for said motor by:determining amaximum allowed torque for said motor based on the speed of said motorand the data in said memory indicating the maximum torque of said motor;and calculating the maximum allowed current for said motor based on themaximum allowed torque of said motor and the coefficients of thetorque-to-current relationship for said motor.
 8. The powered surgicaltool system of claim 6, wherein:said switch includes a control memberlocated outside of said handpiece and a switch sensor located in saidhandpiece, wherein said control member is movable relative to saidswitch sensor and said switch sensor generates the control signal as afunction of the relative position of said control member to said switchsensor; and said memory includes a set of coefficients for correctingthe control signal; and said control console is further configuredto:produce a corrected control signal based on the control signal fromsaid switch sensor and the coefficients for correcting the controlsignal; and apply energization signals to said motor based on thecorrected control signal and the speed of the motor.
 9. The poweredsurgical tool system of claim 6, wherein said memory is disposed in saidhandpiece.
 10. A powered surgical tool system, said system including:apowered surgical handpiece for actuating an attachment, said handpiecehaving a variable speed motor for actuating the attachment, wherein saidmotor is actuated by an energization signal; a manually actuated switchassembly for indicating a speed at which said motor is to be operated,said switch assembly having state sensor that generates a variablecontrol signal that indicates the speed at which said motor is to beoperated, wherein said state sensor is located in said handpiece or in asupplemental component separate from said handpiece; a non-volatilememory integral with said handpiece, said memory containing dataindicating if said state sensor is located in said handpiece; and acontrol console connected to said handpiece for applying energizationsignals to said motor and connected to said memory for reading the datatherein, said control console being configured to:read the data fromsaid memory; if the data in said memory indicates said state sensor isin said handpiece, retrieve from said handpiece the control signal; ifthe data in said memory indicates said state sensor is not in saidhandpiece, retrieve from the supplemental component the control signal;monitor the speed of said motor; and generate the energization signalsto said motor based on the speed of said motor and the control signal.11. The powered surgical tool system of claim 10, wherein:a foot switchassembly is selectively connected to said control console, said footswitch assembly having an auxiliary state sensor that generates thecontrol signal; and said control console is further configuredto:determine if said foot switch assembly is connected to said controlconsole; and if said foot switch assembly is connected to said controlconsole, to generate the energization signals to said motor based on thecontrol signals from said auxiliary state sensor regardless of thepresence of said state sensor in said handpiece.
 12. The surgical toolsystem of claim 10, wherein said memory is disposed in said handpiece.13. A powered surgical tool for actuating an attachment, said toolincluding:a handpiece having a variable speed motor for actuating theattachment, wherein said motor is actuated by an energization signal anda coupling assembly for releasable connecting the attachment to saidmotor; and a non-volatile memory integral with said handpiece, saidmemory having therein data describing the characteristics of theenergization signal to be applied to said motor, said memory includingdata indicating, for a plurality of distinct speeds, the maximum currentsaid motor is allowed to draw.
 14. The powered surgical tool of claim13, wherein said memory includes a first set of data fields that containdata indicating the maximum torque of said motor for a plurality ofdifferent speeds and a second set of data fields that contain thecoefficients of a torque-to-current relationship for said motor.
 15. Thepowered surgical tool of claim 13, wherein said memory further includesdata indicating whether or not an auxiliary sensor is fitted to saidhandpiece, said auxiliary sensor producing an output signal, and, ifsaid auxiliary sensor is fitted to said handpiece, data indicating thetype of output signals produced by said auxiliary sensor.
 16. Thepowered surgical tool of claim 13, wherein said memory is disposed insaid handpiece.
 17. A powered surgical tool for actuating an attachment,said tool including:a handpiece having a power producing unit foractuating the attachment, wherein said power producing unit is actuatedby an energization signal and a coupling assembly for releasablyconnecting the attachment to said power producing unit; a first sensordisposed in said handpiece wherein said first sensor is one from aplurality of different types of sensor and said first sensor produces aspecific type of output signal as function of the type of the sensor; anon-volatile memory integral with said handpiece, said memory havingtherein data descriptive of the energization signals to be applied tosaid power producing unit and data that describes the type of outputsignal produced by said first sensor.
 18. The powered surgical tool ofclaim 17, wherein said memory further includes data definingcoefficients that are used by a processor separate from said handpieceto produce a corrected output signal from the output signal produced bysaid first sensor.
 19. The powered surgical tool of claim 17, whereinsaid first sensor is part of a switch assembly used to control actuationof said power producing unit, said switch assembly having amanually-actuated member and said first sensor is configured to producethe output signal based on actuation of the manually-actuated member.20. The powered surgical tool of claim 19, wherein said switch assemblyincludes a member that is moved relative to said first sensor and saidfirst sensor is configured to produce the output signal as a function ofthe distance of said member to said first sensor.
 21. The poweredsurgical tool of claim 17, wherein said first sensor is configured tomonitor operation of said handpiece and said first sensor produces theoutput signal as a function of the operating state of said handpiecemonitored by said first sensor.
 22. The powered surgical tool of claim21, wherein said first sensor is a temperature sensor configured tomonitor the temperature of said handpiece and is configured to producethe output signal as a function of the temperature of said handpiece.23. The powered surgical tool of claim 17, wherein:a second sensorseparate from said first sensor is disposed in said handpiece, saidsecond sensor being one from the plurality of different types of sensorsand said second sensor produces an output signal wherein the outputsignal of said second sensor is different from the output signalproduced by said first sensor; and said memory further includes datathat describes the type of output signal produced by said second sensor.24. The powered surgical tool of claim 23 wherein:said first sensor ispart of a switch assembly used to control actuation of said handpiecewherein the output signal produced by said first sensor is a function ofa manually actuated switch member; and said second sensor is configuredto monitor operation of said handpiece and said second sensor producesthe output signal as a function of the operating state of said handpiecemonitored by the said second sensor.
 25. The powered surgical tool ofclaim 17, wherein said memory is seated in said handpiece.
 26. A poweredsurgical tool for actuating an attachment, said tool including:ahandpiece having a power consuming unit for actuating the attachment,wherein said power consuming unit is actuated by an energization signaland a coupling assembly for releasable connecting the attachment to saidpower consuming unit; a sensor disposed in said handpiece wherein saidsensor generates an output signal used to control or monitor theoperation of said power consuming unit; and a non-volatile memoryintegral with said handpiece, said memory having therein datadescriptive of the energization signals to be applied to said powerconsuming unit and data defining coefficients that are used by aprocessor remote from said handpiece to define a corrected output signalbased on the output signal produced by said sensor.
 27. The poweredsurgical tool of claim 26, wherein:a switch assembly is attached to saidhandpiece, said switch assembly including a lever that is positioned tomove relative to said sensor and wherein said sensor is part of saidswitch assembly and is configured to vary the output signal producedthereby as a function of the relative distance of said lever to saidsensor.
 28. The powered surgical tool of claim 17, wherein said lever isremovably secured to said handpiece.
 29. The powered surgical tool ofclaim 26, wherein said sensor a temperature sensor is configured to varythe output signal produced thereby as a function of the internaltemperature of said handpiece.
 30. The powered surgical tool of claim26, wherein said memory is seated in said handpiece.
 31. A poweredsurgical tool system, said system including:a handpiece having a powerproducing unit for actuating an attachment, wherein said power producingunit is actuated by an energization signal and a coupling assembly forreleasably connecting the attachment to said power producing unit; asensor disposed in said handpiece wherein said sensor generates a sensoroutput signal used to control or monitor the operation of said powerproducing unit; a non-volatile memory integral with said handpiece, saidmemory having therein data descriptive of the energization signals to beapplied to said power producing unit and data defining coefficients forproducing a corrected sensor output signal based on the sensor outputsignal; and a control console connected to: said handpiece for applyingenergization signals to said power producing unit; said sensor forreceiving the sensor output signal; and to said memory for reading thedata stored therein, said control console configured to:produce acorrected sensor output signal based on the sensor output signal and thecoefficient data in said memory; and selectively apply energizationsignals to said power producing unit based on the corrected sensoroutput signal.
 32. The powered surgical tool system of claim 31,wherein:said sensor is one from a plurality of different types ofsensors and the sensor output signal produced by said sensor is one froma plurality of different types of sensor output signals; said memoryfurther includes data indicating the type of the sensor output signalproduced by said sensor; and said control console is further configuredto:determine from the data in said memory the type of the sensor outputsignal produced by said sensor; and based on the determination of thetype of the sensor output signal, engage in one of a plurality ofdifferent control sequences for regulating the generation of theenergization of said power producing unit based on the corrected outputsignal.
 33. The powered surgical tool system of claim 32, wherein:aswitch assembly is attached to said handpiece to control actuation ofsaid power producing unit, said switch assembly having amanually-actuated member and said sensor forms part of said switchassembly wherein the sensor output signal is based on the actuation ofsaid manually-actuated member; said memory contains data indicating thatsaid sensor output signal represents the user-selected actuation of saidpower producing unit; and said control console, upon reading the data insaid memory, applies energization signals to said power producing unitbased on the corrected sensor output signal.
 34. The powered surgicaltool system of claim 32, wherein:said sensor monitors operation of saidhandpiece and the sensor output signal produced by said sensor isrepresentative of the operating state monitored by said sensor; saidmemory includes data indicating the type of operating state informationrepresented by said sensor output signal and an operating limit for saidhandpiece; said control console, upon reading the data in said memory,compares the corrected sensor output signal to the operating limit and,when the comparison indicates that the operating state of said handpieceexceeds the operating limit, selectively modulates the application ofthe energization signals to said power producing unit.
 35. The poweredsurgical tool system of claim 34, wherein said memory is located in saidhandpiece.
 36. A powered surgical handpiece comprising:a housing; avariable-speed motor disposed in said housing, said motor being actuatedby energization signals; a coupling assembly attached to said housingfor releasably coupling a cutting attachment to said motor; and a memoryintegrally associated with said motor, said memory containing datadescribing the energization signals that are to be applied to saidmotor, data describing whether or not a sensor is present in saidhousing that produces an output signal for controlling the motor ormonitoring the operating state of the handpiece, and, if the sensor ispresent, data describing the type of the sensor output signal and anycoefficients required to produce a corrected sensor output signal. 37.The powered surgical handpiece of claim 36, wherein said memory islocated in said housing.